Probable chaperone. Stimulates ATP hydrolysis and the folding of unfolded proteins mediated by HSPA1A/B (in vitro) .
Subcellular locations: Cytoplasm, Cell membrane, Cytoplasm, Myofibril, Sarcomere, Z line
Cytoplasmic according to  and membrane-associated according to .
Expressed in heart, pancreas and skeletal muscle, and to a lesser extent in brain, placenta and liver.