TRAC Protein, Human (P.pastoris, His)

The constant region of the T cell receptor (TR) alpha chain, represented by the TRAC protein, is a fundamental component of alpha-beta T cell receptors crucial for the immune response. These antigen-specific receptors are present on the surface of T lymphocytes and play a pivotal role in recognizing peptide-major histocompatibility (pMH) complexes displayed by antigen-presenting cells (APC), essential for effective T cell adaptive immunity against pathogens. Binding of the alpha-beta TR to the pMH complex initiates TR-CD3 clustering on the cell surface, activating intracellular LCK that phosphorylates the ITAM motifs of CD3G, CD3D, CD3E, and CD247, facilitating the recruitment of ZAP70. ZAP70, in turn, phosphorylates LAT, assembling the LAT signalosome, which branches signals to the calcium, mitogen-activated protein kinase (MAPK), and nuclear factor NF-kappa-B (NF-kB) pathways. This leads to the mobilization of transcription factors critical for gene expression and essential for T cell growth and differentiation. The T cell repertoire, generated in the thymus through V-(D)-J rearrangement, undergoes intrathymic selection to form a self-major histocompatibility (MH) restricted, non-autoaggressive peripheral T cell pool. Post-thymic interactions with pMH complexes shape the structural and functional avidity of the alpha-beta TR, a heterodimer composed of an alpha and beta chain linked by disulfide bonds. The assembly of alpha-beta TR heterodimers with CD3 coreceptor proteins occurs in the endoplasmic reticulum, forming the TR-CD3 (TcR or TCR). This assembly involves the association of TR alpha and TR beta chains with CD3D-CD3E and CD3G-CD3E heterodimers, respectively, and the final association with the CD247 homodimer, a critical step for transport to the cell surface.