Acts as a co-chaperone and mediates the association of the chaperones HSP70 and HSP90 probably facilitating substrate transfer from HSP70 to HSP90 (PubMed:22005844, PubMed:26267894). Stimulates HSP70 ATPase activity and, in contrast, inhibits HSP90 ATPase activity (PubMed:31525467). Monomer (PubMed:32343703). Homodimer (PubMed:26267894, PubMed:31525467). Forms a complex composed of HOP and chaperones HSP70 and HSP90; the interaction is stronger in the absence of ATP (PubMed:22005844). Interacts (via TPR 1, 2, 3, 7, 8 and 9 repeats) with HSP70 (via C-terminus); the interaction is direct and is stronger in the absence of ATP (PubMed:26267894). Interacts (via TPR 4, 5 and 6 repeats) with HSP90 (via C-terminus); the interaction is direct (PubMed:26267894). Expressed during the parasite blood stage, in trophozoites (at protein level). By heat stress (at protein level). The TPR repeats form 3 domains; the TPR 1 domain is composed of TPR 1, 2 and 3 repeats, the TPR2A domain of TPR 4, 5 and 6 repeats and TPR2B domain of TPR 7, 8 and 9 repeats. Showed to form heterodimers (PubMed:26267894, PubMed:31525467). However in a later study, showed to exist predominantly as a monomer (PubMed:32343703).