Acts as a co-chaperone for HSP90AA1. Mediates the association of the molecular chaperones HSPA8/HSC70 and HSP90. 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). Forms a complex with HSPA8/HSC70, HSPCA/HSP-86 and HSPCB/HSP-84 (PubMed:8999875). Interacts with PACRG. Interacts with EEF1AKMT3 (By similarity). Interacts with HSP90/HSP90AA1; the interaction dissociates the PPP5C:HSP90AA1 interaction. Interacts with FLCN, FNIP1 and FNIP2. Interacts with HSPA8/HSC70 (By similarity). Interacts with HSP90AB1; upon SMYD2-dependent HSP90AB1 methylation (By similarity). The TPR 1 repeat interacts with the C-terminal of HSC70. The TPR 4, 5 and 6 repeats (also called TPR2A domain) and TPR 7, 8 and 9 repeats (also called TPR2B domain) interact with HSP90 (By similarity). In vitro kinase assay failed to detect phosphorylation by MAPKAPK2.