Major histocompatibility complex class I molecule and T-cell receptor (MHC class I and TCR)

Major histocompatibility complex class I molecules are cell surface glycoproteins present on nearly all nucleated cells; they are responsible for presenting intracellularly derived peptide antigens to CD8-positive cytotoxic T lymphocytes[4][5][7]. T-cell receptors are membrane-bound heterodimeric proteins expressed primarily on T cells, responsible for specifically recognizing peptide–MHC complexes and transmitting activation signals into T cells[2][5]. The interaction between MHC class I molecules (presenting antigenic peptides) and T-cell receptors (which selectively bind these pMHC complexes) is central to cellular immunity, facilitating identification and targeted elimination of infected or malignant cells[5][7]. MHC–TCR interaction is essential in pathogen defense, autoimmunity, transplant rejection, and the therapeutic action of multiple immunotherapies[4][5]. Both molecules are highly polymorphic or diverse (MHC) or hypervariable (TCR), enabling recognition of a vast array of antigens but also making them challenging as therapeutic targets due to risks of cross-reactivity, immune escape, or unwanted responses[5][7]. Additional clarification: There is an issue with the target as stated: “Major Histocompatibility Complex class I molecules and T-cell receptors” refers to two distinct but intimately interacting protein families—a molecule presenting antigen and the receptor recognizing it—rather than a single canonical drug target[2][4][5]. Most therapeutic targeting will be directed at one component or will involve modulating the interface or their signaling pathways (e.g., TCR signaling, checkpoint pathways), but not the interface as a single molecular target. Thus, “is_incorrect: true” applies: this is not a single canonical target; structured information should treat each protein separately to maintain scientific precision.

Other names

HLA class I and TCR (in humans)MHC I and TCRMajor histocompatibility antigen, class I, and TCRNull for more specific single targets

Inhibition/enhancement of TCR signaling (immunosuppressants, checkpoint inhibitors); Blocking or redirecting antigen presentation (immunotherapies); Modification of TCR or MHC affinity (engineered TCRs)