STIP1 Homology And U-Box Containing Protein 1 (STUB1)

The CHIP protein encoded by this gene binds to and inhibits the ATPase activity of the chaperone proteins HSC70 and HSP70 and blocks the forward reaction of the HSC70-HSP70 substrate-binding cycle. In addition, CHIP possesses E3 ubiquitin ligase activity and promotes ubiquitylation. CHIP enhances HSP70 induction during acute stress and also mediates its turnover during the stress recovery process. The deduced 303-amino acid protein  has a molecular mass of 35 kD and contains three 34-amino acid TPR domains at its N terminus, a central domain rich in charged residues, and 2 potential nuclear localization signals. Human CHIP shares 97% and 53% amino acid identity with its mouse and Drosophila homologs, respectively, with the highest conservation in the 94 residues of the C terminus.