Cloning of cDNAs for cellular proteins that bind to the retinoblastoma gene product

• Published in: Nature (London) 1991-07, Vol.352 (6332), p.251-254
• Main Authors: Defeo-Jones, Deborah, Huang, Pearl S, Jones, Raymond E, Haskell, Kathleen M, Vuocolo, Gerald A, Hanobik, Michelle G, Huber, Hans E, Oliff, Alien
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Base Sequence; Binding and carrier proteins; Biological and medical sciences; Blotting, Southern; Cancer; Carrier Proteins - genetics; Carrier Proteins - isolation & purification; Carrier Proteins - metabolism; Cellular biology; Cloning; Cloning, Molecular; DNA - genetics; DNA - isolation & purification; Female; Fundamental and applied biological sciences. Psychology; genes; Humans; Intracellular Signaling Peptides and Proteins; Medical research; Molecular Sequence Data; Placenta - physiology; Pregnancy; Proteins; RBP-1 protein; RBP-2 protein; Recombinant Proteins - metabolism; Retinoblastoma Protein - metabolism; Retinoblastoma-Binding Protein 2; Sequence Homology, Nucleic Acid; Tumor Suppressor Proteins
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/352251a0

The E7 transforming protein of human papilloma virus-16 binds to the retinoblastoma gene product (pRb) through a nine-amino-acid segment of E7 (21-29). This segment of E7 is homologous to the pRb-binding domains of the simian virus 40 large T and adenovirus E1A transforming proteins. Each of these viral transforming proteins bind to the same region of pRb. To isolate cellular proteins that interact with this viral protein-binding domain on pRb, we used recombinant pRb to screen a human complementary DNA expression library. Two cDNAs were isolated that encode retinoblastoma binding proteins (RBP-1 and RBP-2). We report here that these RBP genes exist in separate loci and produce discrete messenger RNAs. The predicted amino-acid sequence of these genes showed no homology to known proteins, but both RBPs contain the pRb binding motif conserved between E7, large T and E1A14. In vitro expression of the RBP cDNAs yielded proteins that specifically bound to pRb. Recombinant E7 protein, the E7 21-29 peptide and the homologous RBP-1 peptide inhibited RBP-pRb binding. Mutations introduced into the putative pRb-binding segment in RBP-1 impaired its binding activity. These studies indicate that the cellular RBP-1, RBP-2 and viral E7 proteins interact with pRb through similar domains.