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Updated: May 21, 2026
05:57
Peroxisome Staining in Mammalian Cells Using Peroxisome-Specific Probes
Published on: December 19, 2025
Recent advances in peroxisomal matrix protein import.
Xueqian Liu1, Changle Ma, Suresh Subramani
1Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, United States.
Current Opinion in Cell Biology
|June 12, 2012
Summary
Peroxisomes are vital organelles for cellular metabolism. This study details the protein import cycle, focusing on receptor recycling and cargo release, crucial for preventing peroxisome biogenesis disorders.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Peroxisomes are essential organelles involved in diverse metabolic processes.
- They are crucial for preventing severe human diseases known as peroxisome biogenesis disorders (PBDs).
- Peroxisomal matrix protein import is a complex process involving receptor-mediated translocation.
Purpose of the Study:
- To elucidate the molecular machinery governing the peroxisomal matrix protein import cycle.
- To highlight recent advancements in understanding cargo release and receptor recycling.
- To provide insights into the mechanisms preventing PBDs.
Main Methods:
- Focus on the machinery of peroxisomal matrix protein import.
- Analysis of receptor recycling and degradation pathways.
- Review of recent literature on peroxisomal protein translocation.
Main Results:
- Detailed examination of the peroxisomal matrix protein import cycle.
- Identification of key factors in cargo release.
- Understanding the roles of ubiquitination/deubiquitination and ATP hydrolysis in receptor recycling.
Conclusions:
- The peroxisomal protein import machinery is critical for organelle function.
- Advances in understanding this cycle offer potential therapeutic targets for PBDs.
- Efficient receptor recycling is essential for maintaining peroxisomal homeostasis.
Related Concept Videos
01:27Protein Import into the Peroxisomes
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...
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...
01:19Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
01:39Mitochondrial Precursor Proteins
Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70 chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial precursors...
Most of the mitochondrial precursors...
01:12Porin Insertion in the Outer Mitochondrial Membrane
Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...
01:21Structure of Porins
Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel precursors...