CD8 beta Protein, Human (HEK293, His)

CD8 beta, an integral membrane glycoprotein, plays a pivotal role in the immune response, serving multiple functions against both external and internal threats. In T-cells, its primary function is as a coreceptor for the MHC class I molecule:peptide complex, where antigens presented by class I peptides originate from cytosolic proteins. CD8 beta interacts simultaneously with the T-cell receptor (TCR) and the MHC class I proteins presented by antigen-presenting cells (APCs), recruiting the Src kinase LCK to the vicinity of the TCR-CD3 complex. The presence of a palmitoylation site in the cytoplasmic tail of the CD8B chain facilitates the partitioning of CD8 into plasma membrane lipid rafts, enriching signaling proteins. Once LCK is recruited, it initiates diverse intracellular signaling pathways, phosphorylating various substrates and leading to lymphokine production, motility, adhesion, and activation of cytotoxic T-lymphocytes (CTLs). CD8 beta also plays a critical role in the thymic selection of CD8+ T-cells. At the cell surface, it forms disulfide-linked heterodimers with CD8A and interacts with CD3D, coupling TCR-CD3 with CD8, and also interacts with LCK.