Protein interaction of retinoblastoma gene product pRb110 with M(r) 73,000 heat shock cognate protein.

Both the tumor suppressor gene products, the retinoblastoma sensitivity gene product pRb110 and p53, are found in oligomer complexes with the oncogene products of the DNA tumor viruses. It has been demonstrated that p53 binds to the M(r) 70,000 heat shock protein family. However, the protein association of pRb110 with the M(r) 70,000 heat shock protein family is not yet known. We analyzed the immunoprecipitates made with TYK-nu human ovarial carcinoma cell lysate and anti-pRb110 or anti-heat shock protein monoclonal antibodies. In this paper, we demonstrate that pRb110 is associated with the M(r) 73,000 heat shock cognate protein, but not with the M(r) 72,000 heat shock protein. This selective protein association was also detected in HeLa cervical carcinoma cells. Furthermore, the protein complexes of the M(r) 73,000 heat shock cognate protein and pRb110 were dissociated with the presence of ATP, but not with ADP and the nonhydrolyzable ATP analogue, ATP gamma S. This indicates that the dissociation is dependent on the ATP hydrolysis. These data may suggest an as yet undefined important role of M(r) 73,000 heat shock cognate protein in the cell growth control in collaboration with pRb110.