Function
CD247 is an integral component of the TCR-CD3 complex, found on the surface of T lymphocytes. This complex plays a crucial role in the adaptive immune response. When antigen-presenting cells (APCs) activate the T-cell receptor (TCR), the CD3 chains (CD3D, CD3E, CD3G, and CD3Z) within the TCR-CD3 complex transmit signals across the cell membrane. Each CD3 chain possesses immunoreceptor tyrosine-based activation motifs (ITAMs) in its cytoplasmic domain. Upon TCR engagement, these ITAMs undergo phosphorylation by Src family protein tyrosine kinases LCK and FYN, initiating the activation of downstream signaling pathways. The phosphorylation of CD3Z ITAMs creates multiple docking sites for the protein kinase ZAP70, leading to its phosphorylation and conversion into a catalytically active enzyme. CD247 plays a pivotal role in intrathymic T-cell differentiation. Additionally, it participates in the activity-dependent synapse formation of retinal ganglion cells (RGCs) in both the retina and the dorsal lateral geniculate nucleus (dLGN).