Major histocompatibility complex (MHC) peptide-binding groove (MHC groove)

The Major histocompatibility complex (MHC) peptide-binding groove, also known as the antigen-binding cleft, is a specialized structural domain on MHC Class I and Class II molecules that presents peptide fragments to T-cells [StatPearls, PMID: 30725705]. In MHC Class I, the groove is formed by the alpha-1 and alpha-2 helices over a beta-sheet floor, typically binding 8-10 amino acid peptides, while MHC Class II grooves are open-ended, allowing for longer peptides [NIH, PMID: 10508291]. This site is the nexus of the adaptive immune response, facilitating the recognition of foreign pathogens and mutated cancer neoantigens [Nature, PMID: 22722852]. Therapeutic strategies targeting this site include peptide vaccines that load the groove with specific antigens and TCR-mimetic agents, such as Tebeptafusp, which bind the peptide-MHC complex to redirect T-cell cytotoxicity [PMID: 34555031]. Additionally, certain small molecules like abacavir can occupy the groove, changing the shape of the pocket and the repertoire of presented peptides, which can lead to severe immune-mediated adverse reactions [PMID: 22722852]. Understanding the specificity of this groove is essential for developing personalized immunotherapies and predicting drug toxicities.

Other names

Antigen-binding cleftMHC binding pocketHLA peptide-binding groovePeptide-binding cleft

The mechanism involves the presentation of specific antigenic peptides to T-cell receptors (TCRs) to initiate an immune response, or the pharmacological alteration of the groove's binding specificity by small molecules, which changes the self peptide repertoire and can trigger T-cell activation [PMID: 22722852, PMID: 34555031].