HLA-DRB1

HLA class II histocompatibility antigen, DRB1 beta chain (HLA-DRB1), also known as SS1 or DRB1, is a protein belongs to the HLA class II beta chain paralogs and is encoded by the HLA-DRB1 gene. The class II molecule is a heterodimer which is composed of an alpha (DRA) and a beta chain (DRB), meanwhile, both of them are anchored in the membrane. The class II molecule serves an essential role in the immune system via presenting peptides came from extracellular proteins. In general, these molecules are expressed in antigen presenting cells, such as dendritic cell, macrophages, as well as APC: B lymphocytes.
The beta chain of this molecule is about 26-28 kDa, which is encoded by 6 exons. Specifically, exon one encodes the leader peptide; exons 2 and 3 encode the two extracellular domains; exon 4 encodes the transmembrane domain; and exon 5 encodes the cytoplasmic tail. Importantly, thanks to the DR molecule, the beta chain comprises all the polymorphisms specifying the peptide binding specificities. A great number of HLA-DRB1 alleles have been identified and typing for these polymorphisms is generally done for bone marrow and kidney transplantation. Furthermore, HLA-DRB1 is expressed at a level five times higher than its paralogs DRB3, DRB4 and DRB5. And it is present in all individuals.
Gene ID: 3123
UniProt ID: P01911