HLA-DRA is one of the HLA class II alpha chain paralogues. This class II molecule is a heterodimer consisting of an alpha and a beta 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 alpha chain is approximately 33-35 kDa and its gene contains 5 exons. Exon 1 encodes the leader peptide, exons 2 and 3 encode the two extracellular domains, and exon 4 encodes the transmembrane domain and the cytoplasmic tail. DRA does not have polymorphisms in the peptide binding part and acts as the sole alpha chain for DRB1, DRB3, DRB4 and DRB5.
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Protein Aliases: histocompatibility antigen HLA-DR alpha; HLA class II histocompatibility antigen, DR alpha chain; MHC cell surface glycoprotein; MHC class II antigen DRA
Gene Aliases: HLA-DRA; HLA-DRA1; MLRW
UniProt ID: (Human) P01903
Entrez Gene ID: (Human) 3122
Molecular Function: major histocompatibility complex protein