Identification of cellular proteins that can interact specifically with the T/E1A-binding region of the retinoblastoma gene product.

The SV40 T antigen (T)/adenovirus E1A-binding domain of the retinoblastoma gene product (pRB) has been fused to S. japonicum glutathione S-transferase, and the chimera, bound to insoluble glutathione, was used to search for cellular proteins that can interact specifically with pRB. At least seven such proteins were detected in extracts of multiple human tumor cell lines. These proteins failed to bind to a family of pRB fusion proteins that harbor inactivating mutations in the T/E1A-binding domain and to the wild-type fusion protein in the presence of a peptide replica of the pRB-binding domain of T. Therefore, the binding of one or more of these proteins may contribute to the growth-suppressing function of pRB.