CD3D

CD3D, cluster of differentiation 3D, alias CD3d, T3D. it is derived primarily from T lymphocytes and is a key component of the TCR-CD3 complex. cD3D transmits signals through the CD3D, CD3E, CD3G, and CD3Z chains upon TCR engagement. The cytoplasmic structural domains of these chains contain immunoreceptor tyrosine-based activation motifs (ITAM), which are phosphorylated by Src-family protein tyrosine kinases when the TCR is activated by antigen-presenting cells, thereby activating downstream signaling pathways.
CD3D not only plays a role in signaling for T-cell activation, but is also essential for thymocyte differentiation, contributing to the TCR-CD3 complex's correct intracellular assembly and surface expression.
CD3D also interacts with the co-receptors CD4 and CD8, establishing a functional link between the TCR and the co-receptors, which is essential for the activation and positive selection of CD4 or CD8 T cells.