Grp75, also known as mortalin, is a member of Hsp70 family of chaperone proteins that is not heat-inducible. All members of the family, except HSP 70, are constitutively expressed in primate cells. HSP 70 expression is strongly induced in response to heat stress. Grp75 expression is restricted to the mitochondrial matrix and aids in the translocation and folding of nascent polypeptide chains of both nuclear and mitochondrial origin. Grp75 inactivates the tumor suppressor p53. Studies found that Grp75 is overexpressed in many tumor tissues and immortalized human cell lines, suggesting its role in the tumor formation.
