Related Experiment Video

Updated: Oct 24, 2026

Stability and Structure of Bat Major Histocompatibility Complex Class I with Heterologous β2-Microglobulin
11:17

Stability and Structure of Bat Major Histocompatibility Complex Class I with Heterologous β2-Microglobulin

Published on: March 10, 2021

Thimet oligopeptidase and the stability of MHC class I epitopes in macrophage cytosol

F C Portaro1, M D Gomes, A Cabrera

  • 1Laboratory of Biochemistry and Biophysics, Instituto Butantan, São Paulo, SP, Brazil.

Biochemical and Biophysical Research Communications
|March 2, 1999
PubMed

In this study we investigated the fate of a class of proteasome-generated oligopeptides, exposing them to the crude cytosol of macrophages or to the purified recombinant thimet oligopeptidase. Among the proteasome products of known sequences are MHC class I epitopes, 13 of which were randomly chosen to be used as putative substrates. Surprisingly, our results clearly showed that the majority of the peptides were poorly or not degraded, either by the purified enzyme or by the crude macrophage cytosol. The peptides, which were resistant to hydrolysis, displayed high affinity for the thimet oligopeptidase as competitive inhibitors. Regardless of the fact that our data do not allow prediction of whether or not a specific peptide would be degraded, it seems very likely that the structural features, which rule out the stability of the MHC class I peptides in the cytosol, may have implications in an optimized repertoire selection for antigen presentation.

More Related Videos

Immunopeptidomics: Isolation of Mouse and Human MHC Class I- and II-Associated Peptides for Mass Spectrometry Analysis09:32

Immunopeptidomics: Isolation of Mouse and Human MHC Class I- and II-Associated Peptides for Mass Spectrometry Analysis

Published on: October 15, 2021

A High Throughput MHC II Binding Assay for Quantitative Analysis of Peptide Epitopes07:59

A High Throughput MHC II Binding Assay for Quantitative Analysis of Peptide Epitopes

Published on: March 25, 2014

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,...
Export of Misfolded Proteins out of the ER01:32

Export of Misfolded Proteins out of the ER

After folding, the ER assesses the quality of secretory and membrane proteins. The correctly folded proteins are cleared by the calnexin cycle for transport to their final destination, while misfolded proteins are held back in the ER lumen. The ER chaperones attempt to unfold and refold the misfolded proteins but sometimes fail to achieve the correct native conformation. Such terminally misfolded proteins are then exported to the cytosol by ER-associated degradation or ERAD pathway for...
Receptor Downregulation in MVBs01:15

Receptor Downregulation in MVBs

Multivesicular bodies (MVBs) are mature endosomes that sort ubiquitinated proteins and then fuse with lysosomes to degrade the sorted proteins. Epidermal growth factor (EGF) and its receptor (EGFR) form a complex that can be internalized through endocytosis, sorted into an MVB, and later degraded.
The EGFR can initiate signaling pathways that  lead to cell proliferation, migration, and differentiation. Overexpression of EGFR  stimulates cells to proliferate. Excessive  EGFR activation may...