Human leukocyte antigen B27 (HLA-B27) peptide-binding groove (HLA-B27)

The Human leukocyte antigen B27 (HLA-B27) peptide-binding groove is a specialized structural domain of the MHC class I molecule responsible for presenting endogenous peptides to CD8+ cytotoxic T cells [1.1.1, 1.5.1]. This groove is characterized by six distinct pockets (A-F), with the B-pocket exhibiting a unique preference for peptides containing an arginine residue at the second position (P2) [1.2.1, 1.5.1]. It is central to the pathogenesis of spondyloarthropathies, such as ankylosing spondylitis, primarily through the arthritogenic peptide hypothesis, which posits that the groove presents self-peptides or microbial mimics that trigger an autoimmune response [1.1.3, 1.2.2]. Beyond its role in antigen presentation, the biochemical environment of the groove dictates the folding stability of the HLA-B27 heavy chain; inadequate peptide loading can lead to endoplasmic reticulum stress or the formation of pro-inflammatory cell-surface homodimers [1.4.2, 1.5.3]. Therapeutic research focuses on small molecules or synthetic peptides that can occupy the groove to either block the binding of pathogenic antigens or stabilize the molecule's conformation to prevent aberrant folding [1.3.1, 1.5.3]. While current clinical treatments for associated diseases often target downstream cytokines, the peptide-binding groove remains a high-priority target for developing more specific upstream immunomodulatory therapies [1.3.1, 1.4.1].

Other names

HLA-B27 antigen-binding cleftHLA-B27 peptide-binding pocketMHC class I B27 grooveHLA-B27 binding site

Modulation of antigen presentation, stabilization of protein folding, prevention of HLA-B27 homodimerization, and inhibition of T-cell activation.