Major histocompatibility complex class I protein and T cell receptor (MHC class I (for the protein); TCR (for the receptor))

Major histocompatibility complex class I proteins are transmembrane receptors expressed on almost all nucleated cells[2][4]. They bind intracellular peptides—usually from degraded cytosolic proteins—and present them on the cell surface, where they are scanned by T cell receptors (TCRs) on cytotoxic (CD8+) T lymphocytes[2][4][7]. A specific TCR recognizes a peptide-MHC complex via its highly variable α and β chains, initiating T cell-mediated cytotoxicity or immune response[4][6][7]. This interaction is crucial for clearing virus-infected and malignant cells, and its dysregulation contributes to infection, autoimmunity, and cancer[6][7]. The physical engagement of TCR with peptide-MHC class I is referred to as "MHC restriction." Both MHC class I and TCR are highly polymorphic, ensuring diverse immune recognition but also presenting challenges for transplantation and therapy[5][2][7].

Other names

MHC-I and TCRMajor histocompatibility complex class I molecule and T cell receptorHLA class I and TCR (in humans)pMHC/TCR (peptide/MHC-TCR complex, denotes the ternary complex)

Blocking TCR-MHC class I interaction (prevention of T cell activation); Enhancing TCR signaling (promoting immune response against cancer/infection); Inhibiting downstream TCR signal transduction (immunosuppression); Redirecting TCR specificity (engineered T cells for therapeutic targeting)