HSP65 is a member of the HSP60 family of heat shock proteins. HSP60s are mitochondrial chaperonins that are typically held responsible for the transportation and refolding of proteins from the cytoplasm into the mitochondrial matrix. In addition to its role as a heat shock protein, HSP60 functions as a chaperonin to assist in folding linear amino acid chains into their respective three-dimensional structure. HSP60s are a ubiquitous class of HSPs that specifically promote the folding and assembly of cellular polypeptides in an ATP-dependent manner. Specifically, sequence comparison of HSP65 from different mycobacterium strains showed that the protein sequence of M. bovis BCG is identical to that of M. tuberculosis, and very similar to that of M. leprae, the pathogens that cause tuberculosis and tuberculoid leprosy, respectively. Mycobacterium bovis BCG HSP65 was identified as the immunodominant antigen during mycobacterial diseases and vaccination. It is also believed to be the antigen that induces autoimmune disease, such as adjuvant arthritis in rats.