Human HSPA13 (also called 70kDa heat shock protein 13, STCH, or 'stress 70 protein chaperone, microsome-associated, 60kDa') belongs to the heat shock protein 70 (HSP70) family of chaperones that assist in protein folding and assembly and can direct incompetent 'client' proteins towards degradation. Typically, HSP70s have a nucleotide-binding domain (NBD) and a substrate-binding domain (SBD). The nucleotide sits in a deep cleft formed between the two lobes of the NBD. STCH contains an NBD but lacks an SBD []. STCH may function to regulate cell proliferation and survival, and modulate the TRAIL-mediated cell death pathway. The HSPA13 gene is a candidate stomach cancer susceptibility gene; a mutation in the NBD coding region of HSPA13 has been identified in stomach cancer cells []. The NBD of HSPA13 interacts with the ubiquitin-like proteins Chap1 and Chap2, implicating HSPA13 in regulating cell cycle and cell death events []. HSPA13 is induced by the Ca2+ ionophore A23187 [].
