Recombinant Pig T-cell surface glycoprotein CD3 epsilon chain (CD3E), 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. CD3E ITAM phosphorylation creates docking sites for the protein kinase ZAP70 leading to ZAP70 phosphorylation and its conversion into a catalytically active enzyme. In addition of this role of signal transduction in T-cell activation, CD3E plays an essential role in correct T-cell development (By similarity). Also participates in internalization and cell surface down-regulation of TCR-CD3 complexes via endocytosis sequences present in CD3E cytosolic region (By similarity). In addition to its role as a TCR coreceptor, it serves as a receptor for ITPRIPL1 (By similarity). Ligand recognition inhibits T-cell activation by promoting interaction with NCK1, which prevents CD3E-ZAP70 interaction and blocks the ERK-NFkB signaling cascade and calcium influx (By similarity)

Subcellular Location

Cell membrane (Single-pass type I membrane protein)

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. Interacts with CD6. Interacts (via Proline-rich sequence) with NCK1; the interaction is ligand dependent but independent of tyrosine kinase activation. Interacts with NUMB; this interaction is important for TCR-CD3 internalization and subsequent degradation. Interacts (when tyrosine phosphorylated) with LAG3; disrupting the association between CD3E and LCK and preventing TCR activation

• Wang J. et al. Cloning and sequencing of porcine CD3 epsilon. (JUN-)