The T/E1A-binding domain of the retinoblastoma product can interact selectively with a sequence-specific DNA-binding protein.

A DNA-binding site selection and enrichment procedure revealed a sequence-specific DNA-binding activity selectively associated with glutathione S-transferase-retinoblastoma protein chimeras (GST-RB) that had been incubated with a human cell extract. Appropriate mutant forms of GST-RB, incubated in equivalent extracts, did not associate with this specific DNA-binding activity, and a peptide replica of the HPV E7 RB-binding segment selectively inhibited the association of GST-RB with the sequence-specific DNA-binding protein(s). Sequence analysis of oligonucleotides with high affinity for GST-RB complexes, as well as the results of competition binding studies, strongly suggest that RB can associate specifically with the transcription factor E2F or with a protein having closely related DNA-binding properties.