Suppression Of Tumorigenicity 13 (ST13)

One Hip oligomer bound the ATPase domains of at least 2 Hsc70 molecules, and binding was dependent on activation of the Hsc70 ATPase by Hsp40. Hip stabilized the ADP-bound form of Hsc70, which had a high affinity for a test protein substrate. ST13 is an abundant, highly conserved protein that binds the major cytosolic chaperones heat-shock protein 70-kD (HSP70) and HSP90 during an intermediate stage of steroid receptor assembly, but is absent from the mature receptor complex. The deduced 369-amino acid protein has a calculated molecular mass of approximately 41 kD and an apparent molecular mass of 48 kD by SDS-PAGE. HIP promoted functional maturation of Gccr by enhancing formation of its ligand-binding domain.