Molecular chaperone that functions in the processing and transport of secreted proteins (By similarity). Required for the synthesis of lipophosphoglycan (LPG), a cell surface glycoconjugate (PubMed:12198148). Necessary for the attachment of the galactosyl residue to the mannose within the phosphoglycan repeats of the nascent LPG chain (PubMed:12198148). Also required for addition of phosphoglycan to acid phosphatase (PubMed:12198148). Not required for normal growth (PubMed:12198148). Has ATPase activity (By similarity). Binds heparin with micromolar affinity which may facilitate infection of host cells (By similarity). Homotetramer. Expressed throughout the life cycle with lower expression in stationary phase promastigotes and higher levels in amastigotes. Not induced by stress conditions such as heat, glucose deprivation or treatment with the glycosylation inhibitor tunicamycin. Defective lipophosphoglycan synthesis and reduced levels of the surface glycoproteins gp46 and gp63. Belongs to the heat shock protein 90 family.