Recombinant Human DRB5 protein

DRB5 is a member of the MHC class II β-chain family, encoded by the HLA-DRB5 gene within the human leukocyte antigen (HLA) complex on chromosome 6. It plays a critical role in antigen presentation by forming heterodimers with the MHC class II α-chain (DRA), creating functional HLA-DR molecules expressed on antigen-presenting cells. These molecules bind exogenous peptide antigens and present them to CD4+ T cells, initiating adaptive immune responses. DRB5 is notably associated with the HLA-DR2 haplotype (HLA-DRB1*15:01 and HLA-DRB5*01:01), which has been linked to autoimmune diseases like multiple sclerosis (MS) and susceptibility to certain infections.

Recombinant DRB5 protein refers to the engineered form of this β-chain, produced using expression systems like *E. coli* or mammalian cell lines. It is commonly generated as a soluble, purified protein for research purposes, often co-expressed with DRA to mimic native HLA-DR5 complexes. The recombinant protein retains the peptide-binding groove structure, enabling studies on antigen interaction, T cell receptor (TCR) recognition, and autoimmune epitope mapping. Its production facilitates investigations into HLA-disease associations, particularly in MS, where DRB5-derived peptides may contribute to pathogenic T cell activation.

Researchers utilize DRB5 recombinant proteins to explore mechanisms of immune dysregulation, develop antigen-specific therapies, or screen small-molecule inhibitors targeting pathogenic HLA-peptide-TCR interactions. Structural studies using X-ray crystallography or cryo-EM often employ recombinant DRB5 to elucidate molecular details of antigen presentation. Additionally, it serves as a tool for diagnostic assays detecting autoantibodies or autoreactive T cells in autoimmune conditions. Despite its functional overlap with other HLA-DR β-chains, DRB5's unique genetic linkage and disease associations make it a distinct focus for understanding HLA-mediated immunity and pathology.