HLA-DRB5 belongs to the HLA class II beta chain paralogues. This class II molecule is a heterodimer consisting of an alpha (DRA) and a beta (DRB) chain, both anchored in the membrane. It plays a central role in the immune system by presenting peptides derived from extracellular proteins. Class II molecules are expressed in antigen presenting cells (APC: B lymphocytes, dendritic cells, macrophages). The beta chain is approximately 26-28 kDa and its gene contains 6 exons. 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. Within the DR molecule the beta chain contains all the polymorphisms specifying the peptide binding specificities. Typing for these polymorphisms is routinely done for bone marrow and kidney transplantation. DRB1 is expressed at a level five times higher than its paralogues DRB3, DRB4 and DRB5. The presence of DRB5 is linked with allelic variants of DRB1, otherwise it is omitted. There are 4 related pseudogenes: DRB2, DRB6, DRB7, DRB8 and DRB9.
DR beta 5 chain; DR beta-5; DR-5 beta chain; DR-9; DR2-beta-2; DR9; DRB1-9 beta chain; Dw2; HLA class II histocompatibility antigen; HLA class II histocompatibility antigen, DR beta 5 chain; HLA class II histocompatibility antigen, DR-5 beta chain; HLA class II histocompatibility antigen, DRB1-9 beta chain; HLA-DRB; HLA-DRB5; human leucocyte antigen DRB5; leukocyte antigen class II; MHC class I antigen; MHC class II antigen DRB1*9; MHC class II antigen DRB5; MHC class II HLA beta chain; MHC HLA-DR; MHC HLA-DR-beta cell surface glycoprotein; MHC HLA-DR-beta chain