Related Experiment Video
Updated: Aug 5, 2026
08:49
Fluorescence-Based Measurements of Phosphatidylserine/Phosphatidylinositol 4-Phosphate Exchange Between Membranes
Published on: March 14, 2021
Multiple distinct targeting signals in integral peroxisomal membrane proteins
J M Jones1, J C Morrell, S J Gould
1The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
The Journal of Cell Biology
|June 13, 2001
Summary
Peroxisomal membrane proteins (PMPs) may have multiple targeting signals, challenging previous assumptions. The protein PEX19 interacts with these signals, potentially aiding PMP import into peroxisomes.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Trafficking
Background:
- Peroxisomal proteins are synthesized in the cytoplasm and imported into peroxisomes.
- Targeting signals guide matrix proteins, but signals for membrane proteins (PMPs) are less understood.
- A common assumption is that PMPs possess a single targeting signal.
Purpose of the Study:
- To investigate the targeting mechanisms of integral peroxisomal membrane proteins (PMPs).
- To challenge the assumption of single targeting signals in PMPs.
- To explore the role of PEX19 in PMP import.
Main Methods:
- Analysis of targeting information in PMP34 and PEX13.
- Identification of minimal targeting regions within these PMPs.
- Investigation of PEX19 interactions with PMP34 targeting regions.
Main Results:
- The integral PMP34 contains at least two independent sets of targeting information for peroxisomal membrane insertion.
- The integral PMP PEX13 also possesses two distinct peroxisomal targeting signals.
- PEX19 interacts with the identified minimal targeting regions of PMP34.
Conclusions:
- The findings challenge the prevailing model of single targeting signals for PMPs.
- PMP import may involve novel mechanisms to maintain solubility before membrane insertion.
- PEX19 likely plays a crucial role in the import and biogenesis of peroxisomal membrane proteins.
More Related Videos
Related Concept Videos
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...
01:19Translocation 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,...
01:42Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
01:29Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
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...
01:21Structure 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...