HLA-DRA (Major histocompatibility complex, class II, DR alpha) is one of the HLA class II alpha chain paralogues. It 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. In immunohistochemistry, HLA-DRA has cytoplasmic expression in antigen presenting cells (APC) such as B lymphocytes, dendritic cells, macrophages, and is present in the lung, gastrointestinal tract, kidney, immune tissues, skin, breast and a few other organs throughout the body. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804;