Bu proje NIH hibe EY025290, GM127652 ve Rochester başlangıç finansman Üniversitesi tarafından finanse edildi.

1. BacMam ifade Baculoviruses üreten
<ol><li>BacMam vektör18 GFP 10 tarafından izleyen bir tütün Etch virüs (TEV) proteaz tanıma dizisi ile pEG istenen memeli bestrophin protein kodlama dizisi takın O'nun etiketi-protein C terminus x.</li>
	<li>Geçici ifade plazmid yapıştırıcı HEK293 hücreleri19,20,21,22,23transfect. Ifade 10 X veya 20 X büyütme, 488 nm uyarma kaynak ve 510 nm Emisyon filtre (Şekil 1A) Floresan mikroskop altında GFP-füzyon proteinin denetleyin. Not: Polimer esaslı transfection düzenli olarak plazmid DNA HEK293 hücrelerinin bir 35 mm yemek için 1 μg ile gerçekleştirilir.</li>
	<li>Sf9 böcek hücrelerinde baculoviruses yukarıda açıklanan16,17olarak üretmek. Not: Bölüm 3 (P3) HEK293-F hücrelerin protein üretimi için bulaştırmak için kullanılacak, virüs 4 ° C'de 1 ay boyunca saklanabilir.</li>
	<li>P3 virüs titresi (bulaşıcı adet) tarafından plak oluşumu tahlil16,17belirlemek. Not: ilgi protein GFP ile etiketlenir, bulaşıcı birimleri kontrol etmek için daha hızlı bir yöntem Sf9 hücreleri ile seri dilutions virüs bulaştırmak ve 48 saat sonra floresan hücreleri saymak gibidir.</li>
</ol>2. protein ifade
<ol><li>HEK293-F ifadenin orta 37 ° C oksijen kuluçka % 8 CO2HEK293-F hücrelerle süspansiyon kültürü korumak. Daha kültür Hacim 2 - 2.5 kat daha büyük olan ve kültür 135 devirde yörünge bir platformda döndürmek tek kullanımlık kültür şişeler kullanın. Not: Bu pasajlar 5 ve 30 arasında olduklarında enfekte hücreleri ve hücre kültür başlık altında bu eylemleri gerçekleştirmek için tavsiye edilir.</li>
	<li>24 saat önce viral enfeksiyon, Trypan mavi, 15 μL hücre kültürü için bir 15 μL aliquot ekleyin ve hücre yoğunluğu ve mikroskop altında bir hemasitometre kullanarak canlılığı denetleyin. 0,6 x 106 hücre/mL 2 x 2 L şişeler her biri, 500 mL orta önceden 37 ° C'de ısındı hücrelere sulandırmak Not: Ölü hücreleri mavi Trypan tarafından mavi lekeli. İstenen hücre canlılık olduğunu > % 95.</li>
	<li>Enfeksiyon günü, hücre yoğunluğu ve canlılığı (adım 2.2) denetleyin. Not: Bir yüksek hücre canlılığı > % 95 verimli enfeksiyon ve protein ifade için esastır. ~1.0 x 106 hücre/mL (2 x 500 mL 0,6 x 106 hücre/mL hücre kültürü yetişkin gecede) beklenen cep yoğunluğudur. Hücre beklenen toplam sayısı ~1.0 x 109' dur.</li>
	<li>P3 baculoviruses enfeksiyonu (MOI) 5 çokluğu, hücreleri ekleyin. Aşılamak için virüs miktarı belirlemek için aşağıdaki denklemi kullanarak: <img alt="Equation" src="/files/ftp_upload/57832/57832eq1.jpg">
</li>
	<li>Bir oksijen 37 ° C kuluçka % 8 CO2 24 h 135 rpm'de yörünge platformda hücreleri sallamayın.</li>
	<li>Sodyum bütrat 10 mM hücre kültürü ekleyin ve 48 h için kuluçka devam edin. Not: Sodyum bütrat ek ifade ve istikrarı geliştirmek sonra bazı proteinler, hücre kültürü sıcaklığı 30 ° C ile azaltılması.</li>
	<li>10 X-20 X büyütme, 488 nm uyarma kaynak ve 510 nm Emisyon filtre ile floresan mikroskop altında yüzde ve parlaklık doğrudan protein (bestrophin-GFP-10xHis) verim (Şekil 1B) temsil eden yeşil hücre kontrol. Not: Yeşil hücre yüzdesi tarafından hesaplanır: (yeşil hücreler/toplam hücreleri) x 100. İyi protein ifade düzeyi güçlü yeşil floresan mikroskop altında gösterilir.</li>
	<li>1000 x g 20 dk. Kaldır süpernatant 4 ° c de centrifuging tarafından hücreleri hasat ve hücre topakları fosfat tamponlu tuz (PBS) ~ 80 mL son hacmiyle ile yeniden askıya alma. Split 2 x 50 mL konik boru ve 1000 x g 4 ° c de 20 dakika süreyle santrifüj içine hücre süspansiyon hücre granül-80 ° C'de depolamak</li>
</ol>3. protein saflaştırma
<ol><li>Onlar çözülme 10-15 dakika oda sıcaklığında coşkulu bir su banyosunda hücre granül içeren konik tüpler kuluçkaya. 2 x (w/v) hacmi İndinavir inhibitörleri (Aprotinin, Leupeptin, Pepstatin A ve phenylmethylsulfonyl florür) ile desteklenmiş arabellek (Tablo 1) (Örneğin, hücre Pellet arabellek 20 ml 10 g) hücrelerde 0.1-1.0 yeniden askıya mM. Yukarı ve aşağı damlalıklı kapsamlı bir homojen hücre süspansiyon elde etmek için.</li>
	<li>Yüksek basınçlı bir homogenizer kullanarak hücreleri parçalayıcı. Hücre süspansiyon koşmak-den geçerek homogenizer, 7-10 MPa toplamda 3 - 4 kez tam homojenizasyon elde etmek için. Hücre lysate 2-3 dakika arasında tur için buz üzerinde tutun.</li>
	<li>Deterjan [Örneğin, % 2 w/v sol-grade n-Lauryl-β-D-Maltopyranoside (demir)] lysate hücreye ekleyin. 20 ° C'de membran proteinlerinin ayıklamak için 1 h için ajitasyon ile kuluçkaya. Not: Deterjan türü her protein hedef18,24için optimize edilmiş olması gerekir.</li>
	<li>Bir ultracentrifuge 4 ° c için 1 h 150.000 x g, santrifüj kapasitesi. Not: Aşağıdaki adımları 4 ° C'de gerçekleştirilir</li>
	<li>Açik Hücre lysate ve bunun üzerinden 5 mL O'nun tuzak Ni2 +- NTA benzeşme sütun ile tampon (Tablo 1) önceden equilibrated akış toplamak. Not: Santrifüjü sonra Açik Hücre lysate Pelet alt ve üst bulutlu bir katmanda arasında sıkışmış. 10 mL transfer damlalıklı dikkatle net lysate toplamak ve sonra 1 mL damlalıklı son birkaç lysate mililitre geçmek için kullanın. Ni2 + sütun yapışmasına neden olabilir Pelet kaçının; Ancak, küçük bir miktar üst tabaka yolunda veya 1,5 mikron filtre ile filtre uygulanabilir.</li>
	<li>Sütun arabelleği B 25 mL ve sonra arabellek C 40 mL ile yıkayın (Tablo 2 ve 3, sırasıyla). Not: Bu gibi toplam arıtma en fazla 12 saat sürebilir ve protein gecede sütuna bağlı iken kararlı kalabilir bir ara vermem için iyi bir yer olduğunu.</li>
	<li>Hızlı protein sıvı kromatografi (FPLC) sistemi için sütun ekleyin ve protein arabelleği D 13 mL ile sütun (Tablo 3) ayırma ile elute. UV absorbans okuma göre protein zenginleştirilmiş kesirleri toplamak. Not: FPLC koşulları aşağıdaki gibidir: 1.0 mL kesir boyutu, bir ön sütun basınç alarm 0,3 MPa ve bir akış hızı 0.5 mL/dk için ayarlanmış.</li>
	<li>Microvolume spektrofotometre eluted protein ürün konsantrasyon ölçmek. 280 absorbans okumak nm.</li>
	<li>(İsteğe bağlı) GFP-10xHis etiketi kaldırmak için 1:1 yığın oran TEV proteaz ekleyin ve 30 dk için 4 ° C'de kuluçkaya. Not: Etiketi olabilir veya işlev veya saf kanal yapısını etkileyen değil. Birim ve adımları 3.7-3,8 toplanan protein konsantrasyonu TEV tutarı hesaplamak. Örneğin, elüsyon ürün 10 mL toplanan ve 0.1 mg/mL, toplam protein ölçülen kütlesi olduğunu TEV 10 x 0,1 = 1 mg ve 1 mg sindirim için kullanılacak.</li>
	<li>Protein (50 ya da 100 kDa) 15 mL santrifüj ile konsantre filtre birimi tarafından 4.000 x g 4 ° c (için FPLC bir 2 mL örnek yükleme döngü) 400-500 μL son hacmiyle de iplik. Not: Konsantrasyon için centrifuging zaman konsantrasyon ve protein büyüklüğüne bağlı olarak değişir. Aşırı konsantre önlemek için hangi protein yağış neden olabilir, spin için ilk başta, 10 dk sonra kalan birim gözlemlemek ve tahmin bir sonraki tur time (Örneğin, 2-5 dk), ve benzeri, son hacim elde edilir. Damlalıklı filtre altına çekti protein dağıtmak için spin arasında.</li>
	<li>Yeni 1,5 mL tüp ve herhangi bir çökelti veya baloncuklar konsantre ürün kaldırmak için yoğun protein aktarın. At spin > 12.000 x g 5-10 dk 4 ° C ve süpernatant yeni 1,5 mL tüp içinde toplamak için.</li>
	<li>1 mL şırınga ve bir FPLC sistemde yuvarlak uçlu iğne niyetine boyutu-dışlama kromatografi ile nihai ürün ile tampon E (Tablo 5) önceden dengelenmiş boyutu-dışlama sütun yükleyin. Not: FPLC koşulları aşağıdaki gibidir: 0.5 mL kesir boyutu, bir ön sütun basınç alarm 2.50 MPa için ayarlanmış, bir akış birim arabelleği E 30 mL (Tablo 5), ve bir akış hızı 0.5 mL/dk için ayarlayın.</li>
	<li>Su kuyusu-davranmak proteinler bir tek uç aynı derecede (Şekil 2A) çalıştırmak ve toplamak için bu zirve (Şekil 2A) karşılık gelen protein fraction(s) dikkat edin.</li>
	<li>4 mL veya 0.5 mL santrifüj filtre birimi (aynı molekül ağırlığı kesme adım 3.10 olduğu gibi) ve 4000 x g 4 ° c 5-10 μg/μL son bir konsantrasyon ile spin ile protein konsantre. Spektrofotometre nihai ürün konsantrasyon (adım 3.8) denetlemek için kullanın. Not: nihai ürün birim arıtma denemeler arasında farklı olabilir Santrifüjü zaman, farklı olmadığı sürece. Genellikle, aralıklarla 10-20 dakika sürer. Bu filtre altına çekti protein dağıtmak için spin arasında damlalıklı önerilir.</li>
	<li>Yoğun protein yeni bir 1,5 mL tüp aktarın. Herhangi bir çökelti, centrifuging tarafından Kaldır > 12.000 x g 4 ° C'de 5-10 dk Süpernatant yeni bir 1,5 mL tüp aktarın. -80 ° C'de 10 μL aliquots muhafazası için yapın ve bir 4-%15 degrade SDS-sayfa jel 9 V/cm (Şekil 2B) çalıştırmak için bir 2-5 μL küçük aliquot kaydedin.</li>
	<li>Kütle spektrometresi8tarafından saf protein kimliğini onaylayın. Not: Vitro analiz fonksiyonu ve saf protein yapısını düzlemsel lipid bilayer ve x-ışını kristalografisi, sırasıyla5,8gerçekleştirilebilir.</li>
</ol>

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Bu iletişim kuralı ifade ve gelecekteki vitro analizler için kullanılmak üzere memeli bestrophin iyon kanalları arınma için yararlı bir potansiyel açıklar. FPLC aygıt boyutu-dışlama kromatografi için gerekli olmakla birlikte, bir şırınga pompa benzeşme Kromatografi bağlama, yıkama ve eluting de dahil olmak üzere tüm adımları için yeterli olur. Bir şırınga pompa itme çözümlerinde (şırınga) üzerinden sütun için kullanırken, hava kabarcıkları sütuna iterek önlemek için ba...

Bestrophins iyon kanallarının bakterilerden insanlar1olarak değişen türler ile korunmuş bir aileyiz. İnsanlarda, BEST1 gen, kromozom 11q12.3 üzerinde bulunan membran proteini Bestrophin-1 (BEST1) ağırlıklı olarak retina pigment epiteli (RPE) hücreleri gözleri2,3 demiri membran ifade edilen kodlar. ,4. 585 ilk ~ 350 olan türler arasında son derece korunmuş ve onun transmembran bölge içeren, aminoasitler, oluşan bir CaCC insanlar1,5,6BEST1 görür. Ayrıca, BEST1 homologs tavuklarda ve Klebsiella pneumoniae koruma evrim boyunca yüksek düzeyde düşündüren homopentamers7,8olarak, işlev.
İnsanlarda, 200'den fazla mutasyon BEST1 gen klinik olarak retina dejenerasyonu hastalıklarının bestrophinopathies1,9adlı bir gruba bağlıdır. En iyi hastalık, Yetişkin başlangıçlı vitelliform distrofi, otozomal dominant vitreoretinochoroidopathy, otozomal resesif bestrophinopathy ve retinitis pigmentosa3,4 de dahil olmak üzere beş belirli bestrophinopathies bildirilmiştir ,10,11,12,13,14. Azalan görme ve hatta körlüğe yol açar, bu hastalıkların Şu anda tedavi edilemez. Tedavi tedaviler ve potansiyel olarak Kişiselleştirilmiş tıp geliştirmek için nasıl bu BEST1 hastalığa neden olan mutasyonlar etkisi işlevi ve BEST1 kanal15yapısını anlamak için önemlidir. Bu amaçla, araştırmacılar saf bestrophin (yabani türü ve/veya mutant) kanalları sağlamanız ve vitro analizler5,8yapmak gerekir.
İlk önemli adım bestrophin kanalları memeli hücrelerinde yüksek türlerden ifadesidir. Baculovirus iletim (BacMam sistemi) HEK293-F hücrelerinin zar proteinleri16,17heterologously ifade etmek için güçlü bir yöntem olduğu için bu iletişim kuralı sağlam ifade için en iyi duruma getirilmiş bir BacMam vektörü (pEG BacMam) kullanır Bu durumda bir memeli bestrophin homolog olan hedef protein18. Bu vektör reseptörleri G protein birleştiğinde, nükleer reseptörleri ve diğer iyon kanalları18de dahil olmak üzere çeşitli membran proteinlerinin ifade için kullanılmıştır. Üretilen proteinlerin kristalografisi18için uygun olduğuna dair bir kanıt da vardır. İfade HEK293-F hücrelerdeki yüksek seviyeleri ile proteinler sonra Kromatografi kullanarak saf; Özellikle, bestrophins söz konusu olduğunda, benzeşme ve boyutu-dışlama Kromatografi kullanılabilir.
Bu iletişim kuralı için bir bestrophin kanal ince ayarlı olduğunda, saf protein sonra onun fonksiyonu ve düzlemsel lipid bilayer ve x-ışını kristalografisi, sırasıyla5,8aracılığıyla yapısı için analiz edilebilir. Özet olarak, bu teknikleri bestrophins ve diğer iyon kanalları fonksiyonel ve yapısal incelemeler için güçlü bir boru hattı sağlar.

<table border="0" cellpadding="0" cellspacing="0" width="680">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HEPES</td>
			<td style="width:148px;">Fisher Scientific</td>
			<td style="width:119px;">AC327265000&#160;</td>
			<td style="width:197px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaCl</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">AC446212500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Glycerol</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">G33-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Imidazole</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">AC301870010</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:216px;">MgCl2</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">AC197530010&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">TCEP</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">AA4058704&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Aprotinin</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">AAJ63039MA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Leupeptin</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">AAJ61188MB&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pepstatin A</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">AAJ20037MB</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Phenylmethylsulfonyl fluoride</td>
			<td>Fisher Scientific</td>
			<td style="width:119px;">AC215740050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DDM sol-grade</td>
			<td style="width:148px;">Anatrace</td>
			<td style="width:119px;">D310S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DDM anagrade</td>
			<td style="width:148px;">Anatrace</td>
			<td style="width:119px;">D310</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sf-900 II SFM</td>
			<td style="width:148px;">ThermoFisher</td>
			<td style="width:119px;">10902179</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FreeStyle medium</td>
			<td>ThermoFisher</td>
			<td style="width:119px;">12338018</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NanoDrop spectrophotometer</td>
			<td>ThermoFisher</td>
			<td style="width:119px;">ND-2000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">High pressure homogenizer</td>
			<td style="width:148px;">Avestin</td>
			<td style="width:119px;">Emulsiflex-C5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HisTrap column</td>
			<td style="width:148px;">GE</td>
			<td>17-5248-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Superdex-200 column</td>
			<td style="width:148px;">GE</td>
			<td style="width:119px;">28990944</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">AKTA Pure</td>
			<td style="width:148px;">GE</td>
			<td style="width:119px;">29018224</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ultra-15 centrifugal filter units</td>
			<td style="width:148px;">Millipore</td>
			<td style="width:119px;">UFC910024</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ultra-4 centrifugal filter units</td>
			<td style="width:148px;">Millipore</td>
			<td style="width:119px;">UFC810024</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ultra-0.5 centrifugal filter units</td>
			<td style="width:148px;">Millipore</td>
			<td style="width:119px;">UFC505024</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Optima XE-90 Ultracentrifuge</td>
			<td style="width:148px;">Beckman Coulter</td>
			<td>A94471</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Mini-PROTEAN Tetra Cell</td>
			<td style="width:148px;">Bio-Rad</td>
			<td>1658004</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Mini-PROTEAN precast gel</td>
			<td style="width:148px;">Bio-Rad</td>
			<td>4561084</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">T100 Thermal Cycler</td>
			<td style="width:148px;">Bio-Rad</td>
			<td>1861096</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PolyJet transfection reagent</td>
			<td style="width:148px;">SignaGen</td>
			<td>SL100688</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">pEG BacMam vector</td>
			<td style="width:148px;"></td>
			<td style="width:119px;"></td>
			<td>Obtained from the Gouaux lab at Vollum Institute</td>
		</tr>
	</tbody>
</table>

expression and purification of mammalian bestrophin ion channels

İnsan genomu dört bestrophin paralogs, yani BEST1, BEST2, BEST3 ve BEST4 kodlar. BEST1, BEST1 Gen tarafından kodlanmış olan bir Ca2 +-Cl- ağırlıklı olarak retina pigment epiteli (RPE) ifade kanal (CaCC) aktif. BEST1 fizyolojik ve patolojik önemi olduğunu BEST1 gen 200'den fazla farklı mutasyonların genetik olarak en az beş Retina dejeneratif bozuklukları, en iyi vitelliform gibi bir yelpazede bağlantılı olmuştur aslında tarafından vurgulanır yaşa bağlı makula distrofi (en iyi hastalığı). Bu nedenle, Biyofizik bestrophin kanal tek molekül düzeyinde anlamak çok büyük önemi tutar. Ancak, saflaştırılmış memeli iyon kanalları almak kez zor bir görev olduğunu. Burada, BacMam baculovirus Gen aktarım sistemi ve onların arıtma benzeşme ve boyutu-dışlama kromatografi ile memeli bestrophin proteinlerin ifade için bir protokol raporu. Saf protein sonraki fonksiyonel ve yapısal analizleri, lipid bilayers ve kristalografisi elektrofizyolojik kayıt gibi kullanılmak üzere potansiyeline sahiptir. Önemlisi, bu boru hattı fonksiyonlar ve diğer iyon kanal yapıları çalışmaya adapte edilebilir.

Geçici transfected yapışkanlı HEK293 hücrelerinde (Şekil 1A) Floresan yoğunluğu öngörülen protein ifade düzey süspansiyon HEK293-F hücrelerdeki (Şekil 1B) için iyi bir göstergedir. Hedef protein iyi ifade veya HEK293 hücrelerde sonra geçici transfection yanlış yerelleştirilmiştir değilse, bu ifade yapısı değiştirme göz önünde bulundurun için tavsiye edilir (Örn., GFP etiket konumunu deği...

Watch this Scientific Journal Video about Expression and Purification of Mammalian Bestrophin Ion Channels at JoVE.com

Expression and Purification of Mammalian Bestrophin Ion Channels

İfade ve arıtma memeli Bestrophin iyon kanalları

İyon kanalları arıtma kez, zorlu ama bir kez elde, potansiyel olarak vitro araştırmalar fonksiyonları ve yapıları kanallarının izin verebilirsiniz. Burada, biz ifade ve arıtma memeli bestrophin protein, bir ailenin Ca2 +için kademeli yordamlar açıklar-Cl- kanalları aktif.

The human genome encodes four bestrophin paralogs, namely BEST1, BEST2, BEST3, and BEST4. BEST1, encoded by the BEST1 gene, is a Ca2+-activated Cl- ...

expression-and-purification-of-mammalian-bestrophin-ion-channels

Research

JoVE Journal

Biochemistry

8.3K Görüntüleme.  University of Rochester, School of Medicine and Dentistry. İyon kanalları arıtma kez, zorlu ama bir kez elde, potansiyel olarak vitro araştırmalar fonksiyonları ve yapıları kanallarının izin verebilirsiniz. Burada, biz ifade ve arıtma memeli bestrophin protein, bir ailenin Ca2 +için kademeli yordamlar açıklar-Cl- kanalları aktif.

Video: Expression and Purification of Mammalian Bestrophin Ion Channels

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug used to treat depression and anxiety by binding to the serotonin transporter with high-affinity, blocking serotonin reuptake. Here we report an efficient procedure and a set of tools to stabilize, express, purify, and crystallize serotonin transporter-antibody complexes bound to S-citalopram and other antidepressants. Mutations which stabilize the serotonin transporter were identified using an S-citalopram binding assay. Serotonin transporter expressed in baculovirus-transduced HEK293S GnTI- cells, was reconstituted into proteoliposomes and used to raise high-affinity antibodies. We have developed a strategy to discover antibodies that are useful for structural studies. A straightforward approach for the expression of antibody fragments in Sf9 cells has also been established. Transporter-antibody complexes purified using this procedure are well-behaved and readily crystallize, producing complexes with S-citalopram that diffract X-rays to 3-4 &#197; resolution. The strategies developed here can be utilized to determine the structure of other challenging membrane proteins.

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

This manuscript describes how to screen for thermostabilizing mutations, purify the human serotonin transporter, generate high affinity antibodies, and crystallize the serotonin transporter-antibody complex bound to the antidepressant drug S-citalopram. This protocol can be adapted to the study of other challenging membrane transporters, receptors, and channels.

Termo, İfade, saflaştırılması, ve İnsan serotonin Transporter Kristalizasyon Bound<em&gt; S</em&gt; -citalopram

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug ...

Biyokimya

Expression, Purification, and Antimicrobial Activity of S100A12

Calgranulin proteins are important mediators of innate immunity and are members of the S100 class of the EF-hand family of calcium binding proteins. Some S100 proteins have the capacity to bind transition metals with high affinity and effectively sequester them away from invading microbial pathogens in a process that is termed "nutritional immunity". S100A12 (EN-RAGE) binds both zinc and copper and is highly abundant in innate immune cells such as macrophages and neutrophils. We report a refined method for the expression, enrichment and purification of S100A12 in its active, metal-binding configuration. Utilization of this protein in bacterial growth and viability analyses reveals that S100A12 has antimicrobial activity against the bacterial pathogen, Helicobacter pylori. The antimicrobial activity is predicated on the zinc-binding activity of S100A12, which chelates nutrient zinc, thereby starving H. pylori which requires zinc for growth and proliferation.

Here, we present a method to express and purify S100A12 (calgranulin C). We describe a protocol to measure its antimicrobial activity against the human pathogen H. pylori.

S100A12&#39;nin Ekspresyon, Saflaştırma ve Antimikrobiyal Aktivitesi

Calgranulin proteins are important mediators of innate immunity and are members of the S100 class of the EF-hand family of calcium binding proteins. Some ...

Measurement of Ion Concentration in the Unstirred Boundary Layer with Open Patch-Clamp Pipette: Implications in Control of Ion Channels by Fluid Flow

Fluid flow is an important environmental stimulus that controls many physiological and pathological processes, such as fluid flow-induced vasodilation. Although the molecular mechanisms for the biological responses to fluid flow/shear force are not fully understood, fluid flow-mediated regulation of ion channel gating may contribute critically. Therefore, fluid flow/shear force sensitivity of ion channels has been studied using the patch-clamp technique. However, depending on the experimental protocol, the outcomes and interpretation of data can be erroneous. Here, we present experimental and theoretical evidence for fluid flow-related errors and provide methods for estimating, preventing, and correcting these errors. Changes in junction potential between the Ag/AgCl reference electrode and bathing fluid were measured with an open pipette filled with 3 M KCl. Fluid flow could then shift the liquid/metal junction potential to approximately 7 mV. Conversely, by measuring the voltage shift induced by fluid flow, we estimated the ion concentration in the unstirred boundary layer. In the static condition, the real ion concentrations adjacent to the Ag/AgCl reference electrode or ion channel inlet at the cell-membrane surface can reach as low as approximately 30% of that in the flow condition. Placing an agarose 3 M KCl bridge between the bathing fluid and reference electrode may have prevented this problem of junction potential shifting. However, the unstirred layer effect adjacent to the cell membrane surface could not be fixed in this way. Here, we provide a method for measuring real ion concentrations in the unstirred boundary layer with an open patch-clamp pipette, emphasizing the importance of using an agarose salt-bridge while studying fluid flow-induced regulation of ion currents. Therefore, this novel approach, which takes into consideration the real concentrations of ions in the unstirred boundary layer, may provide useful insight on the experimental design and data interpretation related to fluid shear stress regulation of ion channels.

Mechanosensitive ion channels are often studied in terms of fluid flow/shear force sensitivity with patch-clamp recording. However, depending on the experimental protocol, the outcome on fluid flow-regulations of ion channels can be erroneous. Here, we provide methods for preventing and correcting such errors with a theoretical basis.

Açık yama-kelepçe pipet ile Unstirred sınır tabaka iyonu konsantrasyonu ölçümü: etkileri kontrol altında sıvı iyon kanalları akışı

Fluid flow is an important environmental stimulus that controls many physiological and pathological processes, such as fluid flow-induced vasodilation. ...

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy

Transient receptor potential channels (TRPCs) of the canonical TRP subfamily are nonselective cation channels that play an essential role in calcium homeostasis, particularly store-operated calcium entry, which is critical to maintaining proper function of synaptic vesicle release and intracellular signaling pathways. Accordingly, TRPC channels have been implicated in a variety of human diseases including cardiovascular disorders such as cardiac hypertrophy, neurodegenerative disorders such as Parkinson&#39;s disease, and neurologic disorders such as spinocerebellar ataxia. Therefore, TRPC channels represent a potential pharmacologic target in human diseases. However, the molecular mechanisms of gating in these channels are still unclear. The difficulty in obtaining large quantities of stable, homogeneous, and purified protein has been a limiting factor in structure determination studies, particularly for mammalian membrane proteins such as the TRPC ion channels. Here, we present a protocol for the large-scale expression of mammalian ion channel membrane proteins using a modified baculovirus gene transfer system and the purification of these proteins by affinity and size-exclusion chromatography. We further present a protocol to collect single-particle cryo-electron microscopy images from purified protein and to use these images to determine the protein structure. Structure determination is a powerful method for understanding the mechanisms of gating and function in ion channels.

This protocol describes techniques used to determine ion channel structures by cryo-electron microscopy, including a baculovirus system used to efficiently express genes in mammalian cells with minimum effort and toxicity, protein extraction, purification, and quality checking, sample grid preparation and screening, as well as data collection and processing.

İfade ve insan Lipid duyarlı ba * kanal TRPC3 arınma için tek-parçacık Cryo-elektron mikroskobu ile yapısal kararlılık

Transient receptor potential channels (TRPCs) of the canonical TRP subfamily are nonselective cation channels that play an essential role in calcium ...

Expression, Solubilization, and Purification of Eukaryotic Borate Transporters

The Solute Carrier 4 (SLC4) family of proteins is called the bicarbonate transporters and includes the archetypal protein Anion Exchanger 1 (AE1, also known as Band 3), the most abundant membrane protein in the red blood cells. The SLC4 family is homologous with borate transporters, which have been characterized in plants and fungi. It remains a significant technical challenge to express and purify membrane transport proteins to homogeneity in quantities suitable for&#160;structural or functional studies. Here we describe detailed procedures for the overexpression of borate transporters in Saccharomyces cerevisiae, isolation of yeast membranes, solubilization of protein by detergent, and purification of borate transporter homologs from S. cerevisiae, Arabidopsis thaliana, and Oryza sativa. We also detail a glutaraldehyde cross-linking experiment to assay multimerization of homomeric transporters. Our generalized procedures can be applied to all three proteins and have been optimized for efficacy. Many of the strategies developed here can be utilized for the study of other challenging membrane proteins.

Here we present a protocol to express, solubilize, and purify several eukaryotic borate transporters with homology to the SLC4 transporter family using yeast. We also describe a chemical cross-linking assay to assess the purified homomeric proteins for multimeric assembly. These protocols can be adapted for other challenging membrane proteins.

İfade, Solubilization ve ökaryotik Bor taşıyıcılar arıtma

The Solute Carrier 4 (SLC4) family of proteins is called the bicarbonate transporters and includes the archetypal protein Anion Exchanger 1 (AE1, also ...

Expression and Purification of Nuclease-Free Oxygen Scavenger Protocatechuate 3,4-Dioxygenase

Single molecule (SM) microscopy is used in the study of dynamic molecular interactions of fluorophore labeled biomolecules in real time. However, fluorophores are prone to loss of signal via photobleaching by dissolved oxygen (O2). To prevent photobleaching and extend the fluorophore lifetime, oxygen scavenging systems (OSS) are employed to reduce O2. Commercially available OSS may be contaminated by nucleases that damage or degrade nucleic acids, confounding interpretation of experimental results. Here we detail a protocol for the expression and purification of highly active Pseudomonas putida protocatechuate-3,4-dioxygenase (PCD) with no detectable nuclease contamination. PCD can efficiently remove reactive O2 species by conversion of the substrate protocatechuic acid (PCA) to 3-carboxy-cis,cis-muconic acid. This method can be used in any aqueous system where O2 plays a detrimental role in data acquisition. This method is effective in producing highly active, nuclease free PCD in comparison with commercially available PCD.

Protocatechuate 3,4-dioxygenase (PCD) can enzymatically remove free diatomic oxygen from an aqueous system using its substrate protocatechuic acid (PCA). This protocol describes the expression, purification, and activity analysis of this oxygen scavenging enzyme.

Nükleazsız Oksijen Çöpçü Protocatechuate 3,4-Dioksijenaz İfadesi ve Saflaştırma

Single molecule (SM) microscopy is used in the study of dynamic molecular interactions of fluorophore labeled biomolecules in real time. However, ...

Expression, Purification, Crystallization, and Enzyme Assays of Fumarylacetoacetate Hydrolase Domain-Containing Proteins

Fumarylacetoacetate hydrolase (FAH) domain-containing proteins (FAHD) are identified members of the FAH superfamily in eukaryotes. Enzymes of this superfamily generally display multi-functionality, involving mainly hydrolase and decarboxylase mechanisms. This article presents a series of consecutive methods for the expression and purification of FAHD proteins, mainly FAHD protein 1 (FAHD1) orthologues among species (human, mouse, nematodes, plants, etc.). Covered methods are protein expression in E. coli, affinity chromatography, ion exchange chromatography, preparative and analytical gel filtration, crystallization, X-ray diffraction, and photometric assays. Concentrated protein of high levels of purity (&#62;98%) may be employed for crystallization or antibody production. Proteins of similar or lower quality may be employed in enzyme assays or used as antigens in detection systems (Western-Blot, ELISA). In the discussion of this work, the identified enzymatic mechanisms of FAHD1 are outlined to describe its hydrolase and decarboxylase bi-functionality in more detail.

Expression and purification of fumarylacetoacetate hydrolase domain-containing proteins is described with examples (expression in E. coli, FPLC). Purified proteins are used for crystallization and antibody production and employed for enzyme assays. Selected photometric assays are presented to display the multi-functionality of FAHD1 as oxaloacetate decarboxylase and acylpyruvate hydrolase.

Fumarylacetoasetat Hydrolase etki alanı Içeren proteinleri ifade, arıtma, kristalizasyon ve enzim Asdimleri

Fumarylacetoacetate hydrolase (FAH) domain-containing proteins (FAHD) are identified members of the FAH superfamily in eukaryotes. Enzymes of this ...

Enrichment of Mammalian Tissues and Xenopus Oocytes with Cholesterol

Cholesterol enrichment of mammalian tissues and cells, including Xenopus oocytes used for studying cell function, can be accomplished using a variety of methods. Here, we describe two important approaches used for this purpose. First, we describe how to enrich tissues and cells with cholesterol using cyclodextrin saturated with cholesterol using cerebral arteries (tissues) and hippocampal neurons (cells) as examples. This approach can be used for any type of tissue, cells, or cell lines. An alternative approach for cholesterol enrichment involves the use of low-density lipoprotein (LDL). The advantage of this approach is that it uses part of the natural cholesterol homeostasis machinery of the cell. However, whereas the cyclodextrin approach can be applied to enrich any cell type of interest with cholesterol, the LDL approach is limited to cells that express LDL receptors (e.g., liver cells, bone marrow-derived cells such as blood leukocytes and tissue macrophages), and the level of enrichment depends on the concentration and the mobility of the LDL receptor. Furthermore, LDL particles include other lipids, so cholesterol delivery is nonspecific. Second, we describe how to enrich Xenopus oocytes with cholesterol using a phospholipid-based dispersion (i.e., liposomes) that includes cholesterol. Xenopus oocytes constitute a popular heterologous expression system used for studying cell and protein function. For both the cyclodextrin-based cholesterol enrichment approach of mammalian tissue (cerebral arteries) and for the phospholipid-based cholesterol enrichment approach of Xenopus oocytes, we demonstrate that cholesterol levels reach a maximum following 5 min of incubation. This level of cholesterol remains constant during extended periods of incubation (e.g., 60 min). Together, these data provide the basis for optimized temporal conditions for cholesterol enrichment of tissues, cells, and Xenopus oocytes for functional studies aimed at interrogating the impact of cholesterol enrichment.

Enrichment of Mammalian Tissues and Xenopus Oocytes with Cholesterol

Two methods of cholesterol enrichment are presented: the application of cyclodextrin saturated with cholesterol to enrich mammalian tissues and cells, and the use of cholesterol-enriched phospholipid-based dispersions (liposomes) to enrich Xenopus oocytes. These methods are instrumental for determining the impact of elevated cholesterol levels in molecular, cellular, and organ function.

Memeli Dokuları ve Kenopus Oositlerinin Kolesterol ile Zenginleşmesi

Cholesterol enrichment of mammalian tissues and cells, including Xenopus oocytes used for studying cell function, can be accomplished using a variety of ...

PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase

Structural studies with tryptophan synthase (TS) bienzyme complex (&#945;2&#946;2 TS) from Salmonella typhimurium have been performed to better understand its catalytic mechanism, allosteric behavior, and details of the enzymatic transformation of substrate to product in PLP-dependent enzymes. In this work, a novel expression system to produce the isolated &#945;- and isolated &#946;-subunit allowed the purification of high amounts of pure subunits and &#945;2&#946;2 StTS complex from the isolated subunits within 2 days. Purification was carried out by affinity chromatography followed by cleavage of the affinity tag, ammonium sulfate precipitation, and size exclusion chromatography (SEC). To better understand the role of key residues at the enzyme &#946;-site, site-direct mutagenesis was performed in prior structural studies. Another protocol was created to purify the wild type and mutant &#945;2&#946;2 StTS complexes. A simple, fast and efficient protocol using ammonium sulfate fractionation and SEC allowed purification of &#945;2&#946;2 StTS complex in a single day. Both purification protocols described in this work have considerable advantages when compared with previous protocols to purify the same complex using PEG 8000 and spermine to crystalize the &#945;2&#946;2 StTS complex along the purification protocol. Crystallization of wild type and some mutant forms occurs under slightly different conditions, impairing the purification of some mutants using PEG 8000 and spermine. To prepare crystals suitable for x-ray crystallographic studies several efforts were made to optimize crystallization, crystal quality and cryoprotection. The methods presented here should be generally applicable for purification of tryptophan synthase subunits and wild type and mutant &#945;2&#946;2 StTS complexes.

This article presents a series of consecutive methods for the expression and purification of Salmonella typhimurium tryptophan synthase comp this protocol a rapid system to purify the protein complex in a day. Covered methods are site-directed mutagenesis, protein expression in Escherichia coli, affinity chromatography, gel filtration chromatography, and crystallization.

PCR Mutagenezi, Klonlama, İfade, Hızlı Protein Saflaştırma Protokolleri ve Triptofan Synthase'in Vahşi Tipinin ve Mutant Formlarının Kristalizasyonu

Structural studies with tryptophan synthase (TS) bienzyme complex (&#945;2&#946;2 TS) from Salmonella typhimurium have been performed to better understand ...

Ganglioside Extraction, Purification and Profiling

Gangliosides are glycosphingolipids that contain one or more sialic acid residues. They are found on all vertebrate cells and tissues but are especially abundant in the brain. Expressed primarily on the outer leaflet of the plasma membranes of cells, they modulate the activities of cell surface proteins via lateral association, act as receptors in cell-cell interactions and are targets for pathogens and toxins. Genetic dysregulation of ganglioside biosynthesis in humans results in severe congenital nervous system disorders. Because of their amphipathic nature, extraction, purification, and analysis of gangliosides require techniques that have been optimized by many investigators in the 80 years since their discovery. Here, we describe bench-level methods for the extraction, purification, and preliminary qualitative and quantitative analyses of major gangliosides from tissues and cells that can be completed in a few hours. We also describe methods for larger scale isolation and purification of major ganglioside species from brain. Together, these methods provide analytical and preparative scale access to this class of bioactive molecules.

Gangliosides are sialic acid-bearing glycosphingolipids that are particularly abundant in the brain. Their amphipathic nature requires organic/aqueous extraction and purification techniques to ensure optimal recovery and accurate analyses. This article provides overviews of analytic and preparative scale ganglioside extraction, purification, and thin layer chromatography analysis.

Ganglioside Ekstraksiyonu, Saflaştırma ve Profilleme

Gangliosides are glycosphingolipids that contain one or more sialic acid residues. They are found on all vertebrate cells and tissues but are especially ...