Molecular chaperone; assists the folding of proteins upon ATP hydrolysis. Known to play a role, in vitro, in the folding of actin and tubulin. In yeast may play a role in mitotic spindle formation. Heterooligomeric complex of about 850 to 900 kDa that forms two stacked rings, 12 to 16 nm in diameter. Present with 5530 molecules/cell in log phase SD medium. Belongs to the TCP-1 chaperonin family.