The 'active life' of Hsp90 complexes

► The regulatory role of co-chaperones in the formation of Hsp90 complexes is reviewed. ► I summarize the role of Hsp90 co-chaperones that regulate the ATPase cycle of Hsp90. ► The role of post-translational modification on the Hsp90 chaperone cycle. ► Hsp90s active site although highly conserved can mutate without loss of function.