CD3G
Domain
A di-leucine motif and a tyrosine-based motif are individually sufficient to induce both endocytosis and delivery to lysosomes.
Function
Part of the TCR-CD3 complex present on T-lymphocyte cell surface that plays an essential role in adaptive immune response. When antigen presenting cells (APCs) activate T-cell receptor (TCR), TCR-mediated signals are transmitted across the cell membrane by the CD3 chains CD3D, CD3E, CD3G and CD3Z. All CD3 chains contain immunoreceptor tyrosine-based activation motifs (ITAMs) in their cytoplasmic domain. Upon TCR engagement, these motifs become phosphorylated by Src family protein tyrosine kinases LCK and FYN, resulting in the activation of downstream signaling pathways (PubMed:2470098). In addition to this role of signal transduction in T-cell activation, CD3G plays an essential role in the dynamic regulation of TCR expression at the cell surface (PubMed:8187769). Indeed, constitutive TCR cycling is dependent on the di-leucine-based (diL) receptor-sorting motif present in CD3G.
Involvement in disease
Immunodeficiency 17
IMD17
An autosomal recessive primary immunodeficiency characterized by highly variable clinical severity. Some patients have onset of severe recurrent infections in early infancy that may be lethal, whereas others may be only mildly affected or essentially asymptomatic into young adulthood. More severely affected patients may have evidence of autoimmune disease or enteropathy. The immunologic pattern is similar among patients, showing partial T-cell lymphopenia, decreased amounts of the CD3 complex, and impaired proliferative responses to T-cell receptor dependent stimuli. The phenotype in some patients is reminiscent of severe combined immunodeficiency.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
Phosphorylated on Tyr residues after T-cell receptor triggering by LCK in association with CD4/CD8 (PubMed:2470098). Phosphorylated also by PKC; leading to the TCR complex down-regulation (PubMed:8187769).
Phosphorylated on Tyr residues after T-cell receptor triggering by LCK in association with CD4/CD8.
Cellular localization
- Cell membrane
- Single-pass type I membrane protein
Alternative names
CD3g, T3G, CD3G, T-cell surface glycoprotein CD3 gamma chain, T-cell receptor T3 gamma chain