Related Experiment Video

Updated: May 15, 2026

Using Fluorescent Proteins to Monitor Glycosome Dynamics in the African Trypanosome
10:04

Using Fluorescent Proteins to Monitor Glycosome Dynamics in the African Trypanosome

Published on: August 19, 2014

Processing of the glycosomal matrix-protein import receptor PEX5 of Trypanosoma brucei

Melisa Gualdrón-López1, Paul A M Michels

  • 1Research Unit for Tropical Diseases, de Duve Institute, Université catholique de Louvain, Brussels, Belgium.

Biochemical and Biophysical Research Communications
|December 26, 2012
PubMed

Insights

Trypanosoma brucei PEX5 protein exists in two forms due to parasite proteases. The 72kDa form, derived from the 100kDa form, remains functional for targeting matrix proteins to glycosomes.

Area of Science:

  • Cell Biology
  • Parasitology
  • Molecular Biology

Background:

  • Glycolysis in Trypanosoma brucei occurs in glycosomes, requiring protein import via the PEX5 receptor.
  • PEX5 recognizes the peroxisomal-targeting signal type 1 (PTS1) on matrix proteins.
  • PEX5 is susceptible to proteolytic processing.

Purpose of the Study:

  • To investigate the different forms of PEX5 detected in T. brucei.
  • To determine the functional implications of PEX5 processing.
  • To identify the role of parasite proteases in PEX5 modification.

Main Methods:

  • Western blotting to detect PEX5 forms.
  • 5'-RACE-PCR to analyze TbPEX5 transcript.
  • In vitro protease susceptibility assays on native and labeled PEX5.
  • SDS-PAGE analysis of recombinant PEX5.

Main Results:

  • Two PEX5 forms (100kDa and 72kDa) were detected in T. brucei.
  • TbPEX5 is encoded by a unique transcript, yielding a maximum 72kDa protein.
  • Recombinant PEX5 shows aberrant migration (100kDa), similar to native PEX5.
  • Protease assays revealed N-terminal truncation of 100kDa PEX5 to 72kDa by unknown proteases.
  • The 72kDa PEX5 form retains PTS1 binding functionality.

Conclusions:

  • T. brucei PEX5 undergoes N-terminal truncation by parasite proteases, generating a functional 72kDa form.
  • This processing affects PEX5 migration in SDS-PAGE.
  • Understanding PEX5 processing is crucial for glycosomal protein import in trypanosomes.

More Related Videos

High-throughput Gene Tagging in Trypanosoma brucei11:26

High-throughput Gene Tagging in Trypanosoma brucei

Published on: August 12, 2016

Purification of Extracellular Trypanosomes, Including African, from Blood by Anion-Exchangers (Diethylaminoethyl-cellulose Columns)14:26

Purification of Extracellular Trypanosomes, Including African, from Blood by Anion-Exchangers (Diethylaminoethyl-cellulose Columns)

Published on: April 6, 2019

Related Concept Videos

Translocation of Proteins into the Mitochondria01:19

Translocation 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,...
Protein Import into the Peroxisomes01:27

Protein 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...
Protein Transport into the Inner Mitochondrial Membrane01:34

Protein 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...
Mitochondrial Protein Sorting01:39

Mitochondrial Protein Sorting

Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death.  Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Mitochondrial Precursor Proteins01:39

Mitochondrial 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...
Protein Transport to the Inner Chloroplast Membrane01:18

Protein Transport to the Inner Chloroplast Membrane

Proteins targeted to the inner chloroplast membrane, or plastid proteins, are transported by two general pathways: the stop-transfer and the re-insertion or post-import pathways. Most plastid proteins carry N-terminal transit sequences and internal import sequences targeting it to the specific chloroplast subcompartment. Proteins targeted by the stop-transfer pathway have internal hydrophobic sequences that inhibit their translocation into the stroma. As a result, these precursors are arrested...