Co-chaperone that binds to numerous kinases and promotes their interaction with the Hsp90 complex, resulting in stabilization and promotion of their activity. Inhibits HSP90AA1 ATPase activity (By similarity). Probably forms a complex composed of chaperones HSP90 and HSP70, co-chaperones STIP1/HOP, CDC37, PPP5C, PTGES3/p23, TSC1 and client protein TSC2 (By similarity). Probably forms a complex composed of chaperones HSP90 and HSP70, co-chaperones CDC37, PPP5C, TSC1 and client protein TSC2, CDK4, AKT, RAF1 and NR3C1; this complex does not contain co-chaperones STIP1/HOP and PTGES3/p23 (By similarity). Forms a complex with Hsp90/HSP90AB1 and CDK6 (By similarity). Interacts with HSP90AA1 (By similarity). Interacts with AR, CDK4, CDK6 and EIF2AK1 (By similarity). Interacts with RB1 (By similarity). Interacts with KSR1 (PubMed:10409742). Interacts with FLCN, FNIP1 and FNIP2 (By similarity). Constitutively sumoylated by UBE2I. Belongs to the CDC37 family.