Displays temperature-dependent chaperone activity. Monomer. Interacts with HSPB1. Interacts with DNAJB6. Interacts with BAG3 (PubMed:28144995). Translocates to nuclear foci during heat shock. Predominantly expressed in skeletal muscle and heart. By 17-beta-estradiol. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the small heat shock protein (HSP20) family. Was reported to have a protein kinase activity and to act as a Mn(2+)-dependent serine-threonine-specific protein kinase.