V region of the variable domain of T cell receptor (TR) alpha chain that participates in the antigen recognition (PubMed:24600447). Alpha-beta T cell receptors are antigen specific receptors which are essential to the immune response and are present on the cell surface of T lymphocytes. Recognize peptide-major histocompatibility (MH) (pMH) complexes that are displayed by antigen presenting cells (APC), a prerequisite for efficient T cell adaptive immunity against pathogens (PubMed:25493333). Binding of alpha-beta TR to pMH complex initiates TR-CD3 clustering on the cell surface and intracellular activation of LCK that phosphorylates the ITAM motifs of CD3G, CD3D, CD3E and CD247 enabling the recruitment of ZAP70. In turn ZAP70 phosphorylates LAT, which recruits numerous signaling molecules to form the LAT signalosome. The LAT signalosome propagates signal branching to three major signaling pathways, the calcium, the mitogen-activated protein kinase (MAPK) kinase and the nuclear factor NF-kappa-B (NF-kB) pathways, leading to the mobilization of transcription factors that are critical for gene expression and essential for T cell growth and differentiation (PubMed:23524462). The T cell repertoire is generated in the thymus, by V-(D)-J rearrangement. This repertoire is then shaped by intrathymic selection events to generate a peripheral T cell pool of self-MH restricted, non-autoaggressive T cells. Post-thymic interaction of alpha-beta TR with the pMH complexes shapes TR structural and functional avidity (PubMed:15040585). Alpha-beta TR is a heterodimer composed of an alpha and beta chain; disulfide-linked. The alpha-beta TR is associated with the transmembrane signaling CD3 coreceptor proteins to form the TR-CD3 (TcR or TCR). The assembly of alpha-beta TR heterodimers with CD3 occurs in the endoplasmic reticulum where a single alpha-beta TR heterodimer associates with one CD3D-CD3E heterodimer, one CD3G-CD3E heterodimer and one CD247 homodimer forming a stable octomeric structure. CD3D-CD3E and CD3G-CD3E heterodimers preferentially associate with TR alpha and TR beta chains, respectively. The association of the CD247 homodimer is the last step of TcR assembly in the endoplasmic reticulum and is required for transport to the cell surface. There are several alleles. The sequence shown is that of IMGT allele TRAV36/DV7*01.