Recombinant Human T-cell surface glycoprotein CD3 gamma chain (CD3G), partial

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 CD247/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

Subcellular Location

Cell membrane (Single-pass type I membrane protein)

Disease Association

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. [The disease is caused by variants affecting the gene represented in this entry]

Subunit

The TCR-CD3 complex is composed of a CD3D-CD3E and a CD3G-CD3E heterodimers that preferentially associate with TCRalpha and TCRbeta, respectively, to form TCRalpha-CD3E-CD3G and TCRbeta/CD3G-CD3E trimers. In turn, the hexamer interacts with CD247/CD3Z homodimer to form the TCR-CD3 complex. Alternatively, TCRalpha and TCRbeta can be replaced by TCRgamma and TCRdelta

• Krissansen G.W. et al. Primary structure of the T3 gamma subunit of the T3/T cell antigen receptor complex deduced from cDNA sequences: evolution of the T3 gamma and delta subunits. — EMBO J. (1986)
• Tunnacliffe A. et al. Physical linkage of three CD3 genes on human chromosome 11. — EMBO J. (1987)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)
• Alexander D. et al. Dephosphorylation of the human T lymphocyte CD3 antigen. — Eur. J. Biochem. (1989)
• Davies A.A. et al. The human T3 gamma chain is phosphorylated at serine 126 in response to T lymphocyte activation. — J. Biol. Chem. (1987)
• Barber E.K. et al. The CD4 and CD8 antigens are coupled to a protein-tyrosine kinase (p56lck) that phosphorylates the CD3 complex. — Proc. Natl. Acad. Sci. U.S.A. (1989)
• Letourneur F. et al. A novel di-leucine motif and a tyrosine-based motif independently mediate lysosomal targeting and endocytosis of CD3 chains. — Cell (1992)
• Arnaiz-Villena A. et al. Brief report: primary immunodeficiency caused by mutations in the gene encoding the CD3-gamma subunit of the T-lymphocyte receptor. — N. Engl. J. Med. (1992)