Major histocompatibility complex, class II, DQ beta 1 is one of two proteins that are required to form the DQ heterodimer, a cell surface receptor essential to the function of the immune system.HLA-DQB1 belongs to the HLA class II beta chain paralogues. This class II molecule is a heterodimer consisting of an alpha (DQA) and a beta chain (DQB), both anchored in the membrane. It plays a central role in the immune system by presenting peptides derived from extracellular proteins.

The beta chain is approximately 26-28 kDa and it contains 5 exons. Exon one encodes the leader peptide, exons 2 and 3 encode the two extracellular protein domains, exon 4 encodes the transmembrane domain and exon 5 encodes the cytoplasmic tail.