T-cell surface glycoprotein CD3 gamma chain (CD3G)

Part of this TCR-CD3 complex present on T-lymphocyte cell surface which plays an essential role in adaptive immune response. When antigen presenting cells (APCs) trigger T-cell receptor (TCR), TCR-mediated signals are transmitted throughout the cell membrane from the CD3 chains CD3D, CD3E, CD3G and CD3Z.

All of 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).