Chaperonin 10 (cpn10) is the ~10kD mammalian equivalent to GroES of E. coli. Chaperonins play fundamental roles in the folding, assembly and translocation of other proteins. Chaperonin function in vivo requires two distinct family members, cpn60 and cpn10, both of which are also present in chloroplasts and mitochondria. The best studied cpn60 and cpn10, are the GroEL and GroES proteins of E. coli, respectively. Cpn10 and cpn60 both exhibit sevenfold axis of symmetry and function as a team in the protein folding and assembly processes. Chaperonin 10 has been located in human platelets but more importantly it may also be present in human maternal serum. It has been reported that human cpn10 is identical with early pregnancy factor (EPF), which is involved in control over cell growth and development. This identification suggests that cpn10 may act like a hormone in stressful situations such as pregnancy. Recombinant Chaperonin 10 protein (human) is also known as Heat Shock Protein 10 (Hsp10) or Mitochondrial Hsp10. It is reported to be identical to Early Pregnancy Factor (EPF).