Enables Hsp90 protein binding activity. Acts upstream of or within chaperone-mediated protein folding. Predicted to be located in Golgi apparatus; cytosol; and nuclear speck. Is expressed in several structures, including alimentary system; central nervous system; genitourinary system; respiratory system; and retina. Orthologous to human UNC45A (unc-45 myosin chaperone A). [provided by Alliance of Genome Resources, Apr 2022]