Sign In

Cells contain membrane-bound organelles called peroxisomes that oxidize organic molecules by transferring hydrogen atoms to oxygen, producing hydrogen peroxide. Peroxisomes enzymatically convert the released hydrogen peroxide into water and oxygen.

Peroxisomal Protein Import:

Peroxisomes lack the genetic machinery required to code for their own proteins. Hence, most peroxisomal membrane, lumenal and transmembrane proteins are synthesized in the cytoplasm or ER and transported to the peroxisome by a group of proteins called peroxins. Peroxisomal receptors recognize the cytosolic proteins by short import sequences at their C- or N-terminus as PTS1 and PTS2, respectively. Proteins from the ER are packaged into specialized vesicles that help transport and insert the protein into the membrane. Unlike other systems such as mitochondria, peroxisomal import machinery can transport fully folded proteins. PEX genes encode for peroxin proteins. Around fifteen PEX genes coding for 32 proteins are known in humans.

Peroxisomal diseases:

The absence or malfunctioning of peroxisomal enzymes in animals results in many metabolic disorders. For example, Zellweger syndrome, an inherited human disease, occurs due to the lack of peroxisomal enzymes or “empty peroxisomes.” Mutations in the Pex5 gene, which encodes peroxin, and defects in the Pex7 gene, which encodes a receptor, cause one form of Zellweger, leading to severe brain, kidney, and liver abnormalities. Adrenoleukodystrophy is a rare X-linked genetic defect that affects the transport and oxidation of long-chain fatty acids in the peroxisomes resulting in the accumulation of fatty acids in the bloodstream. This disease also leads to myelin damage in neurons, affecting the brain's white matter.

Tags
PeroxisomesProtein ImportPTS1PTS2PeroxinsPEX GenesZellweger SyndromeAdrenoleukodystrophyMembrane ProteinsLumenal ProteinsTransmembrane ProteinsCytoplasmERVesiclesMembrane InsertionMetabolic DisordersGenetic Defects

From Chapter 15:

article

Now Playing

15.20 : Protein Import into the Peroxisomes

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

3.1K Views

article

15.1 : The Endoplasmic Reticulum

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

8.2K Views

article

15.2 : Smooth Endoplasmic Reticulum

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

4.5K Views

article

15.3 : Role of ER in the Secretory Pathway

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

3.6K Views

article

15.4 : Directing Proteins to the Rough Endoplasmic Reticulum

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

6.0K Views

article

15.5 : Protein Translocation Machinery on the ER Membrane

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

3.9K Views

article

15.6 : Cotranslational Protein Translocation

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

6.0K Views

article

15.7 : Post-translational Translocation of Proteins to the RER

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

4.7K Views

article

15.8 : Insertion of Single-pass Transmembrane Proteins in the RER

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

5.7K Views

article

15.9 : Insertion of Multi-pass Transmembrane Proteins in the RER

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

6.7K Views

article

15.10 : Tail-anchoring of Proteins in the ER Membrane

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

2.9K Views

article

15.11 : GPI Anchoring of Proteins in the ER Membrane

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

3.6K Views

article

15.12 : Protein Modifications in the RER

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

4.3K Views

article

15.13 : Protein Folding Quality Check in the RER

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

3.2K Views

article

15.14 : Export of Misfolded Proteins out of the ER

Transmembrane Transport in Endoplasmic Reticulum and Peroxisomes

3.0K Views

See More

JoVE Logo

Privacy

Terms of Use

Policies

Research

Education

ABOUT JoVE

Copyright © 2025 MyJoVE Corporation. All rights reserved