축소 솔루션 제조법은 RW 알드리치의 연구실에서입니다. 보건 국립 연구소, 국립 과학 재단 (National Science Foundation), 미국 심장 협회, 근육질 영양 장애 협회, 도널드 B.와 델리아 E. 백스터 재단 Klingenstein 기금과 신경 과학에 대한 맥나이트 엔다우먼트 : 우리는 지원을위한 다음과 같은 자금 지원 기관 및 재단 감사드립니다.

1 부 : vitelline 막 제거 <ol><li> 포셉 두 세트를 준비합니다. 우리는 한 세트가 약간 파일을 날카롭게되어 제 5 포셉를 선호합니다. 또한 7 &quot;파스퇴르 피펫을 트리밍하고 불을 연마하여 유리 전송 피펫을 준비합니다. </li><li> 추천 : 늑대의 oocytes을 방지하기 위해, 그리드의 서클 (1mm의 사각형)을 잘라 60mm 페트리 접시의 바닥에 접착제. 사용하는 사이에 청소 보관하면이 음식은 무기한으로 활용할 수 있습니다. </li><li> 해부 현미경 hyperosmotic 솔루션 (제조법 참조) 장소 중간 페트리 접시를 채우십시오. </li><li> 그릇에 광택 파스퇴르 피펫과 장소와 함께 자신의 인큐베이션 솔루션 1-3 Xenopus의 oocytes를 제​​거합니다. </li><li> 정 잠깐 만요 - 전지 2 분을 축소하기 시작합니다. 긴 시간은 껍질에 세포가 쉽게, 짧은 시간이 패치에 대한 건강한 세포로 이어집니다. </li><li> 셀 축소로 vitelline 막의 세포 위에 투명한 레이어로 거의 표시되기 시작합니다. 필링에 대한 건강한 세포 (whorls 또는 결함없이)를 선택합니다. </li><li> 포셉 한 쌍의로 부드럽게 플라즈마 막을 손상시키지 않고 vitelline 막를 파악. 다른과 함께 같은 장소 근처에 파악하고 부드럽게 떨어져 맑은 멤브레인 찢어하고 세포의 무료입니다. </li><li> 파스퇴르 피펫으로 조심스럽게 녹화 실로 셀 이동합니다. 셀 vitelline 제거 후 연약됩니다. </li></ol> 2 부 : Gigaseal 세대 <ol><li> 식염수에 기록 피펫을 입력합니다. 피펫 커패시턴스를 최소화하기 위해 전극 와이어 잘 전기적 접촉을 만드는 솔루션의 최소 볼륨을 사용합니다. </li><li> 거품이 전극 와이어에 부동 및 슬라이드 수 있도록 피펫 여러 번 버려. 채워진 피펫에 압력을 적용합니다. 이것은 입이나 애완 동물 가게에서 수족관 펌프로 할 수 있습니다. 이 압력은 액체 인터페이스와 세포로 이동을 교차으로 피펫은 청소 유지하는 것이 중요합니다. </li><li> 챔버에서 oocyte를 찾아 세포의 가장자리에 크게 중점을두고 있습니다. </li><li> 목욕, 중심 세포 위에 (초점) 팁 밖으로 피펫으로. 이 최소화 시간은 인감 생성하기 전에 욕조에 보냈습니다. </li><li> 셀 옆에 선명하게 피펫을 드롭 다운. 근접 (~ 50 미크론)로 가져와. 이 솔루션의 작은 변형이 다시 압력에 의한 피펫 밖으로 밀려납니다. </li><li> 패치 클램프 소프트웨어를 사용하여 피펫의 저항을 확인 (우리의 목표는 약 3-4 MΩ입니다)와 오프셋 전압을 사용하여 전류를 제로. </li><li> 시각 저항을 모니터링이나 주파수 저항에 비례하는 음색을 생성 오디오 모니터를 사용하면서 피펫에 긍정적인 압력으로, 세포쪽으로 천천히 팁을 이동합니다. 팁이 세포를 만져 시작으로, 저항은 증가합니다. </li><li> 갑자기하지만 부드럽게 거의 동일한 절대값의 부정적인 압력에 긍정에서 전환합니다. 저항이 형성 밀봉을 증가한다. </li><li> 시간의 대다수는, 인감 형성은 몇 초 이내에 발생, 가끔 30-60초이 필요합니다. </li><li> 저항 1GΩ에되면, 압력은 중립에 공개하실 수 있습니다. 이제 온 세포 패치를했습니다. 내부 아웃 패치, 빠르게 세포에서 멀리 당기십시오. 외부 출력은 아래를 참조하십시오. </li></ol> 제 5 부 : 외부 아웃 토폴로지 (옵션) <ol><li> 즉시 gigaseal, 파열 멤브레인 달성 후. 이것은 날카로운 흡입과 함께 할,하지만 우리가 한 MS에 1 V 펄스를 선호하실 수 있습니다. 저항은 초기 피펫의 저항보다 약간 더 많은 드롭한다. </li><li> 멀리 천천히, 그리고 부드럽게 세포에서 피펫을 이동합니다. 당신은 피펫으로 세포 당겨의 섹션을 참조해야합니다. 갑자기, 그리고 몇 초 이내에, 세포는 다시 스냅되고 저항은 즉시 동시에 GΩs로 돌아합니다. </li><li> 이제 외부 출력 구성에 패치를했습니다. 모든 포함된 이온 채널의 ectodomains은 목욕에 노출됩니다. </li></ol> 파트 6 : 예상 결과 일반적으로, 높은 저항 물개가 선호하고 더 이상 살고있다. 10 GΩ 품질이 우수한 밀봉을위한 좋은 지침이다. 우리의 경험에서이 품질의 바다표범을 얻는 확률은 품질 특히 셀 및 피펫 많은 요인과 다를 수 있습니다. 패치 수집 요금은 건강한 세포, 깨끗한 pipettes, 그리고 경험 연구원 95 % 이상 수 있습니다. 이러한 패치는 몇 분 동안 마지막으로 단일 채널 녹음을 포함한 Xenopus oocytes의 표현 이온 채널의 electrophysiological 연구에 적합합니다.

<ol>
	<li>Neher, E., Sakmann, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-channel+currents+recorded+from+membrane+of+denervated+frog+muscle+fibres.">Single-channel currents recorded from membrane of denervated frog muscle fibres.</a> Nature. 260, 799-802 (1976).</li><li>Sackmann, B., Neher, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Single-channel Recording. , (1983).</li></ol>

여기에 논의하지 electrophysiological 녹음 많은 매개 변수가 있습니다. 릭 설치, 시스템 소음 관리, 채널 표현 및 기록 프로토콜은 모든 좋은 실험 결과 또한 중요합니다. 우리의 경험에서, 이들은 안정적인 물개를 형성을위한 가장 중요한 파라미터 : 목욕을 입력하면 고품질 oocytes는 (일명, &quot;필링&quot;) 빠르게 vitelline 막 제거, 먼지로부터 보호 새로 가져온 pipettes 부드러운 pipettes, 적용 긍정적인 압력을 사용?...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Patch Clamp Amplifier & Software</td>
<td>Instrument</td>
<td>HEKA or Axon</td>
<td>EPC-10</td>
<td>Or other similar device (e.g. HEKA EPC-9 or Axopatch 200B)</td>
</tr>
<tr>
<td>No. 5 forceps (two pairs)</td>
<td>Tool</td>
<td>Fine Science Tools</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Oocyte shrinking solution</td>
<td>Reagent</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Ingredient In mM
N-methyl-D-glucamine 220
HEPES 10
MgCl2 1
EGTA 10
Aspartic Acid 220
KCl 2
pH to 7.4 w/ N-methyl-D-glucamine</td>
</tr>
<tr>
<td>woven mesh</td>
<td>800 um</td>
<td>Spectrum Laboratories INC</td>
<td>146481</td>
<td>&nbsp;</td>		</tbody>
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patch clamp recording of ion channels expressed in  xenopus oocytes

Sakmann 및 Neher 1, 2에 의해 개발 이후, 패치 클램프 세포에서 하나 또는 여러 개의 이온 채널의 electrophysiological 측정을위한 매우 유용한 기술로 설립되었다. 이 기술들은 기본 환경 모두에서 이온 채널에 적용 및 아프리카 발톱 개구리, Xenopus laevis oocytes에서 수확으로 heterologous 세포에 표현할 수있다. 여기, 우리는 Xenopus의 oocytes에서 패치 클램프 녹음의 잘 설립 기법을 설명합니다. 이 기술은 개별적으로 인구 (macropatch) 또는 (단일 채널 녹음)에 어느 표현 이온 채널의 속성을 측정하는 데 사용됩니다. 우리는 oocyte 준비 및 인감 세대의 품질을 극대화하기 위해 기술에 중점을두고 있습니다. 모든 요소가 최적으로,이 기법은 90 % 이상 성공 인감 세대의 가능성을 제공합니다. 과정은 그 또는 그녀가 가장 중요한 발견 요인에 따라 모든 연구자가 다르게 최적화, 우리는 우리 손에 가장 큰 성공으로 이어질있는 방법을 제시 수도 있습니다.

Watch this Scientific Journal Video about Patch Clamp Recording of Ion Channels Expressed in  Xenopus Oocytes at JoVE.com

Patch Clamp Recording of Ion Channels Expressed in  Xenopus Oocytes

이것은 Xenopus laevis oocytes에서 클​​램프의 녹음 패치에 대한 소개로서 것입니다. 그것은 vitelline 막 제거, gigaohm 인감 (gigaseal)의 형성, 그리고 외부 아웃 토폴로지에 패치의 선택 변환을 다룹니다.

Xenopus Oocytes의 표현 이온 채널 패치 클램프 녹음

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological ...

patch-clamp-recording-of-ion-channels-expressed-in-xenopus-oocytes

Research

JoVE Journal

Biology

26.0K 조회수.  Stanford University. 이것은 Xenopus laevis oocytes에서 클​​램프의 녹음 패치에 대한 소개로서 것입니다. 그것은 vitelline 막 제거, gigaohm 인감 (gigaseal)의 형성, 그리고 외부 아웃 토폴로지에 패치의 선택 변환을 다룹니다.

비디오: Patch Clamp Recording of Ion Channels Expressed in  Xenopus Oocytes

Methods for Patch Clamp Capacitance Recordings from the Calyx

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal. Electrical recordings from the presynaptic terminal allow the measurement of action potentials, calcium channel currents, vesicle fusion (exocytosis) and subsequent membrane uptake (endocytosis). The fusion of vesicles containing neurotransmitter causes the vesicle membrane to be added to the cell membrane of the calyx. This increase in the amount of cell membrane is measured as an increase in capacitance. The subsequent reduction in capacitance indicates endocytosis, the process of membrane uptake or removal from the calyx membrane. Endocytosis, is necessary to maintain the structure of the calyx and it is also necessary to form vesicles that will be filled with neurotransmitter for future exocytosis events. Capacitance recordings at the calyx of Held have made it possible to directly and rapidly measure vesicular release and subsequent endocytosis in a mammalian CNS nerve terminal. In addition, the corresponding postsynaptic activity can be simultaneously measured by using paired recordings. Thus a complete picture of the presynaptic and postsynaptic electrical activity at a central nervous system synapse is achievable using this preparation. Here, the methods for slice preparation, morphological features for identification of calyces of Held, basic patch clamping techniques, and examples of capacitance recordings to measure exocytosis and endocytosis are presented.

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal.

칼리에서 패치 클램프 커패시턴스 레코딩을위한 방법

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal. ...

연구

생물학

Pressure-polishing Pipettes for Improved Patch-clamp Recording

Pressure-polishing is a method for shaping glass pipettes for patch-clamp recording. We first developed this method for fabricating pipettes suitable for recording from small (&lt;3 m) neuronal cell bodies. The basic principal is similar to glass-blowing and combines air pressure and heat to modify the shape of patch pipettes prepared by a conventional micropipette puller. It can be applied to so-called soft (soda lime) and hard (borosilicate) glasses. Generally speaking, pressure polishing can reduce pipette resistance by 25% without decreasing the diameter of the tip opening (Goodman and Lockery, 2000). It can be applied to virtually any type of glass and requires only the addition of a high-pressure valve and fitting to a microforge. This technique is essential for recording from ultrasmall cells (&lt;5 m) and can also improve single-channel recording by minimizing pipette resistance. The blunt shape is also useful for perforated-patch clamp recording since this tip shape results in a larger membrane bleb available for perforation.

This is a guide to modifying the shape of glass micropipettes. Specifically, by using heat and air pressure the taper is widened without increasing the tip opening, leading to lower pipette resistance. This is critical to obtain low noise recordings of small cells but is useful in many applications.

향상된 패치 - 클램프 녹음 압력 연마 Pipettes

Pressure-polishing is a method for shaping glass pipettes for patch-clamp recording.  We first developed this method for fabricating pipettes suitable for ...

Microinjection of Xenopus Laevis Oocytes

Microinjection of Xenopus laevis oocytes followed by thin-sectioning electron microscopy (EM) is an excellent system for studying nucleocytoplasmic transport. Because of its large nucleus and high density of nuclear pore complexes (NPCs), nuclear transport can be easily visualized in the Xenopus oocyte. Much insight into the mechanisms of nuclear import and export has been gained through use of this system (reviewed by Pant&eacute;, 2006). In addition, we have used microinjection of Xenopus oocytes to dissect the nuclear import pathways of several viruses that replicate in the host nucleus. 
Here we demonstrate the cytoplasmic microinjection of Xenopus oocytes with a nuclear import substrate. We also show preparation of the injected oocytes for visualization by thin-sectioning EM, including dissection, dehydration, and embedding of the oocytes into an epoxy embedding resin. Finally, we provide representative results for oocytes that have been microinjected with the capsid of the baculovirus Autographa californica nucleopolyhedrovirus (AcMNPV) or the parvovirus Minute Virus of Mice (MVM), and discuss potential applications of the technique.

Here we demonstrate cytoplasmic microinjection of Xenopus laevis oocytes with a nuclear import substrate, as well as preparation of the injected oocytes for visualization by thin-sectioning electron microscopy.

Xenopus Laevis의 Oocytes의 Microinjection

Microinjection of Xenopus laevis oocytes followed by thin-sectioning electron microscopy (EM) is an excellent system for studying nucleocytoplasmic ...

Visualizing RNA Localization in Xenopus Oocytes

RNA localization is a conserved mechanism of establishing cell polarity. Vg1 mRNA localizes to the vegetal pole of Xenopus laevis oocytes and acts to spatially restrict gene expression of Vg1 protein. Tight control of Vg1 distribution in this manner is required for proper germ layer specification in the developing embryo. RNA sequence elements in the 3' UTR of the mRNA, the Vg1 localization element (VLE) are required and sufficient to direct transport. To study the recognition and transport of Vg1 mRNA in vivo, we have developed an imaging technique that allows extensive analysis of trans-factor directed transport mechanisms via a simple visual readout. 
To visualize RNA localization, we synthesize fluorescently labeled VLE RNA and microinject this transcript into individual oocytes. After oocyte culture to allow transport of the injected RNA, oocytes are fixed and dehydrated prior to imaging by confocal microscopy. Visualization of mRNA localization patterns provides a readout for monitoring the complete pathway of RNA transport and for identifying roles in directing RNA transport for cis-acting elements within the transcript and trans-acting factors that bind to the VLE (Lewis et al., 2008, Messitt et al., 2008). We have extended this technique through co-localization with additional RNAs and proteins (Gagnon and Mowry, 2009, Messitt et al., 2008), and in combination with disruption of motor proteins and the cytoskeleton (Messitt et al., 2008) to probe mechanisms underlying mRNA localization.

Visualizing RNA Localization in Xenopus Oocytes

Visualization of in vivo RNA transport is accomplished by microinjection of fluorescently labeled RNA transcripts into Xenopus oocytes, followed by confocal microscopy.

머릿속 RNA 현지화에서 Xenopus Oocytes

RNA localization is a conserved mechanism of establishing cell polarity.  Vg1 mRNA localizes to the vegetal pole of Xenopus laevis oocytes and acts to ...

Fertilization of Xenopus oocytes using the Host Transfer Method

Studying the contribution of maternally inherited molecules to vertebrate early development is often hampered by the time and expense necessary to generate maternal-effect mutant animals. Additionally, many of the techniques to overexpress or inhibit gene function in organisms such as Xenopus and zebrafish fail to sufficiently target critical maternal signaling pathways, such as Wnt signaling. In Xenopus, manipulating gene function in cultured oocytes and subsequently fertilizing them can ameliorate these problems to some extent. Oocytes are manually defolliculated from donor ovary tissue, injected or treated in culture as desired, and then stimulated with progesterone to induce maturation. Next, the oocytes are introduced into the body cavity of an ovulating host female frog, whereupon they will be translocated through the host's oviduct and acquire modifications and jelly coats necessary for fertilization. The resulting embryos can then be raised to the desired stage and analyzed for the effects of any experimental perturbations. This host-transfer method has been highly effective in uncovering basic mechanisms of early development and allows a wide range of experimental possibilities not available in any other vertebrate model organism.

Fertilization of Xenopus oocytes using the Host Transfer Method

Procedure for fertilizing Xenopus oocytes by the host transfer method.

의 수정 Xenopus의 oocytes 호스트 전송 방법을 사용하여

Studying the contribution of maternally inherited molecules to vertebrate early development is often hampered by the time and expense necessary to ...

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying potassium (referred to as GIRK) channels, which are important for regulating the excitability of neurons. There are four different mammalian GIRK channel subunits (GIRK1-GIRK4) - we focus on GIRK2 because it forms a homotetramer. Stimulation of different types of G protein-coupled receptors (GPCRs), such as the muscarinic receptor (M2R), leads to activation of GIRK channels. Alcohol also directly activates GIRK channels. We will show how to mutate one amino acid by specifically changing one or more nucleotides in the cDNA for the GIRK channel. This mutated cDNA sequence will be amplified in bacteria, purified, and the presence of the point mutation will be confirmed by DNA sequencing. The cDNAs for the mutated and wild-type GIRK channels will be transfected into human embryonic kidney HEK293T cells cultured in vitro. Lastly, whole-cell patch-clamp electrophysiology will be used to study the macroscopic potassium currents through the ectopically expressed wild-type or mutated GIRK channels. In this experiment, we will examine the effect of a L257W mutation in GIRK2 channels on M2R-dependent and alcohol-dependent activation.

We will demonstrate how to study the effect of a single point mutation on the function of an ion channel.

이온 채널의 돌연변이 유발과 기능 분석 Heterologously 포유 동물 세포에 표현

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying ...

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may also be used to study the structure-function relationship for other ion channels and neurotransmitter receptors1. BK channels are widely expressed in different tissues and have been implicated in many physiological functions, including regulation of smooth muscle contraction, frequency tuning of inner hair cells and regulation of neurotransmitter release2-6. BK channels are activated by membrane depolarization and by intracellular Ca2+ and Mg2+ 6-9. Therefore, the protocol is designed to control both the membrane voltage and the intracellular solution. In this protocol, messenger RNA of BK channels is injected into Xenopus laevis oocytes (stage V-VI) followed by 2-5 days of incubation at 18&deg;C10-13. Membrane patches that contain single or multiple BK channels are excised with the inside-out configuration using patch clamp techniques10-13. The intracellular side of the patch is perfused with desired solutions during recording so that the channel activation under different conditions can be examined. To summarize, the mRNA of BK channels is injected into Xenopus laevis oocytes to express channel proteins on the oocyte membrane; patch clamp techniques are used to record currents flowing through the channels under controlled voltage and intracellular solutions.

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

Ionic current of BK channels is recorded using patch clamp techniques. BK channels are expressed in Xenopus oocytes by injecting messenger RNA. The intracellular solution during patch clamp recordings is controlled by a perfusion system.

이온 채널 유학을위한 패치 클램프 및 재관류 기법으로 표현 Xenopus oocytes

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may ...

Optimized Transfection Strategy for Expression and Electrophysiological Recording of Recombinant Voltage-Gated Ion Channels in HEK-293T Cells

The in vitro expression and electrophysiological recording of recombinant voltage-gated ion channels in cultured human embryonic kidney cells (HEK-293T) is a ubiquitous research strategy. HEK-293T cells must be plated onto glass coverslips at low enough density so that they are not in contact with each other in order to allow for electrophysiological recording without confounding effects due to contact with adjacent cells. Transfected channels must also express with high efficiency at the plasma membrane for whole-cell patch clamp recording of detectable currents above noise levels. Heterologous ion channels often require long incubation periods at 28&deg;C after transfection in order to achieve adequate membrane expression, but there are increasing losses of cell-coverslip adhesion and membrane stability at this temperature. To circumvent this problem, we developed an optimized strategy to transfect and plate HEK-293T cells. This method requires that cells be transfected at a relatively high confluency, and incubated at 28&deg;C for varying incubation periods post-transfection to allow for adequate ion channel protein expression. Transfected cells are then plated onto glass coverslips and incubated at 37&deg;C for several hours, which allows for rigid cell attachment to the coverslips and membrane restabilization. Cells can be recorded shortly after plating, or can be transferred to 28&deg;C for further incubation. We find that the initial incubation at 28&deg;C, after transfection but before plating, is key for the efficient expression of heterologous ion channels that normally do not express well at the plasma membrane. Positively transfected, cultured cells are identified by co-expressed eGFP or eGFP expressed from a bicistronic vector (e.g. pIRES2-EGFP) containing the recombinant ion channel cDNA just upstream of an internal ribosome entry site and an eGFP coding sequence. Whole-cell patch clamp recording requires specialized equipment, plus the crafting of polished recording electrodes and L-shaped ground electrodes from borosilicate glass. Drug delivery to study the pharmacology of ion channels can be achieved by directly micropipetting drugs into the recording dish, or by using microperfusion or gravity flow systems that produce uninterrupted streams of drug solution over recorded cells.

Reliable method for highly efficient in vitro expression and subsequent electrophysiological recording of recombinant voltage-gated ion channels in cultured human embryonic kidney cells (HEK-293T).

표현과 HEK - 293T 세포의 재조합 전압 - 게이 티드 이온 채널 Electrophysiological 녹음에 최적화된 Transfection 전략

The in vitro expression and electrophysiological recording of recombinant voltage-gated ion channels in cultured human embryonic kidney cells (HEK-293T) ...

Giant Liposome Preparation for Imaging and Patch-Clamp Electrophysiology

The reconstitution of ion channels into chemically defined lipid membranes for electrophysiological recording has been a powerful technique to identify and explore the function of these important proteins. However, classical preparations, such as planar bilayers, limit the manipulations and experiments that can be performed on the reconstituted channel and its membrane environment. The more cell-like structure of giant liposomes permits traditional patch-clamp experiments without sacrificing control of the lipid environment.
Electroformation is an efficient mean to produce giant liposomes &gt;10 &mu;m in diameter which relies on the application of alternating voltage to a thin, ordered lipid film deposited on an electrode surface. However, since the classical protocol calls for the lipids to be deposited from organic solvents, it is not compatible with less robust membrane proteins like ion channels and must be modified. Recently, protocols have been developed to electroform giant liposomes from partially dehydrated small liposomes, which we have adapted to protein-containing liposomes in our laboratory.
We present here the background, equipment, techniques, and pitfalls of electroformation of giant liposomes from small liposome dispersions. We begin with the classic protocol, which should be mastered first before attempting the more challenging protocols that follow. We demonstrate the process of controlled partial dehydration of small liposomes using vapor equilibrium with saturated salt solutions. Finally, we demonstrate the process of electroformation itself. We will describe simple, inexpensive equipment that can be made in-house to produce high-quality liposomes, and describe visual inspection of the preparation at each stage to ensure the best results.

Reconstituting functional membrane proteins into giant liposomes of defined composition is a powerful approach when combined with patch-clamp electrophysiology. However, conventional giant liposome production may be incompatible with protein stability. We describe protocols for producing giant liposomes from pure lipids or small liposomes containing ion channels.

이미징 및 패치 클램프 전기 생리학에 대한 거대한 리포좀 준비

The reconstitution of ion channels into chemically defined lipid membranes for electrophysiological recording has been a powerful technique to identify ...

The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

The cut-open oocyte Vaseline gap (COVG) voltage clamp technique allows for analysis of electrophysiological and kinetic properties of heterologous ion channels in oocytes. Recordings from the cut-open setup are particularly useful for resolving low magnitude gating currents, rapid ionic current activation, and deactivation. The main benefits over the two-electrode voltage clamp (TEVC) technique include increased clamp speed, improved signal-to-noise ratio, and the ability to modulate the intracellular and extracellular milieu.
Here, we employ the human cardiac sodium channel (hNaV1.5), expressed in Xenopus oocytes, to demonstrate the cut-open setup and protocol as well as modifications that are required to add voltage clamp fluorometry capability.
The properties of fast activating ion channels, such as hNaV1.5, cannot be fully resolved near room temperature using TEVC, in which the entirety of the oocyte membrane is clamped, making voltage control difficult. However, in the cut-open technique, isolation of only a small portion of the cell membrane allows for the rapid clamping required to accurately record fast kinetics while preventing channel run-down associated with patch clamp techniques.
In conjunction with the COVG technique, ion channel kinetics and electrophysiological properties can be further assayed by using voltage clamp fluorometry, where protein motion is tracked via cysteine conjugation of extracellularly applied fluorophores, insertion of genetically encoded fluorescent proteins, or the incorporation of unnatural amino acids into the region of interest1. This additional data yields kinetic information about voltage-dependent conformational rearrangements of the protein via changes in the microenvironment surrounding the fluorescent molecule.

The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

The cut-open Vaseline gap approach is used to obtain low noise recordings of ionic and gating currents from voltage-dependent ion channels expressed in Xenopus oocytes with high resolution of fast channel kinetics. With minor modification, voltage clamp fluorometry can be coupled to the cut-open oocyte protocol.

<em&gt; Xenopus의</em형광 측정으로&gt; 난자 절개 바셀린 갭 전압 클램프 기술

The cut-open oocyte Vaseline gap (COVG) voltage clamp technique allows for analysis of electrophysiological and kinetic properties of heterologous ion ...