Chaperonin 10, otherwise known as Cpn10, (groES in E.coli) make up a family of small heart shock proteins with an approximate molecular mass of 10kDa (Hsp10s). Cpn10 acts as a co-chaperone and interacts with the Hsp60 family to promote proper folding of polypeptides. Cpn10 and Cpn60 both exhibit sevenfold axis of symmetry and function as a team in the protein folding and assembly process (1). Cpn10 has been located in human platelets, but is also present in human maternal serum (2, 3). It has been reported that human Cpn10 is
identical with early pregnancy factor, which is involved in control over cell growth and development. This identification suggest that Cpn10 may act like a hormone in stressful situations such as pregnancy (4).