Co-chaperone that binds to numerous proteins and promotes their interaction with Hsp70 and Hsp90. Self-associates. Forms complexes with Hsp70 and Hsp90. Interacts with CDC37, FKBP4, PPID and STIP1. Expressed in brain, heart, kidney, liver, placenta and skeletal muscle. Belongs to the CDC37 family. Truncated C-terminus.