BAG3 and cardiomyopathy: Chaperone proteins play a central role in maintaining cardiac myocyte protein quality, and mutations in CRYAB (HSPB5), HSP27 (HSPB7), HSPB6, HSPB8, and cochaperones such as BAG3 are implicated in the pathogenesis of human cardiomyopathies by affecting stability, localization, or turnover of sarcomeric proteins (9).