Implicated in mitochondrial protein import and macromolecular assembly. May facilitate the correct folding of imported proteins. May also prevent misfolding and promote the refolding and proper assembly of unfolded polypeptides generated under stress conditions in the mitochondrial matrix (By similarity). Forms a single seven-member ring complex, in tight association with the p63 protein. Testis. From the second half of the larval final-instar, through the first two days of pupal development. Shows ATPase activity. Belongs to the chaperonin (HSP60) family.