CD5 (protein)

CD5 (protein)

Identifiers Symbols CD5; LEU1; T1 External IDs OMIM: 153340 MGI: 88340 HomoloGene: 7260 GeneCards: CD5 Gene

Gene Ontology
Molecular function	• glycoprotein binding • receptor activity • transmembrane signaling receptor activity • scavenger receptor activity • protein binding
Cellular component	• plasma membrane • integral to plasma membrane • external side of plasma membrane • fully spanning plasma membrane
Biological process	• cell recognition • cell proliferation • T cell costimulation
Sources: Amigo / QuickGO

RNA expression pattern More reference expression data Orthologs Species Human Mouse Entrez 921 12507 Ensembl ENSG00000110448 ENSMUSG00000024669 UniProt P06127 P13379 RefSeq (mRNA) NM_014207.3 NM_007650.3 RefSeq (protein) NP_055022.2 NP_031676.3 Location (UCSC) Chr 11:
60.87 – 60.9 Mb Chr 19:
10.72 – 10.74 Mb PubMed search

CD5 is a cluster of differentiation found on a subset of IgM-secreting B cells called B-1 cells, and also on T cells. B-1 cells have limited diversity of their B-cell receptor due to their lack of the enzyme terminal deoxynucleotidyl transferase (TdT) and are potentially self-reactive. CD5 serves to mitigate activating signals from the BCR so that the B-1 cells can only be activated by very strong stimuli (such as bacterial proteins) and not by normal tissue proteins. CD5 was used as a T-cell marker until monoclonal antibodies against CD3 were developed.

In humans, the gene is located on the long arm of chromosome 11. There is no ligand confirmed, even if CD72, a C-type lectin, may be considered a probable ligand.

T cells express higher levels of CD5 than B cells. CD5 is upregulated on T cells upon strong activation. In the thymus, there is a correlation with CD5 expression and strength of the interaction of the T cell towards self-peptides.