Displays temperature-dependent chaperone activity. Monomer. Interacts with HSPB1 (By similarity). Interacts with DNAJB6 (By similarity). Interacts with BAG3 (By similarity). Translocates to nuclear foci during heat shock. Highly expressed in skeletal muscle, heart, uterus, liver, lung and ovary. Low levels found in stomach and brain. Not detected in small intestine, large intestine, kidney, spleen and testis. In the ovary, expression is concentrated in the endometrium and in the connective tissue between the circular and longitudinal muscles of the myometrium. Detected in developing heart throughout embryonic development but only detected in developing liver close to time of birth. In the adult ovary, expression is highest during decidualization and early pregnancy. By progesterone. Belongs to the small heat shock protein (HSP20) family.