The retinoblastoma protein copurifies with E2F-I, an E1A-regulated inhibitor of the transcription factor E2F.
Recently, we identified an inhibitory protein, E2F-I, that blocks the DNA-binding activity of the transcription factor E2F. We also showed that the adenovirus E1A protein reverses this inhibitory activity of E2F-I, thereby restoring the DNA-binding activity of E2F. We have now further purified this inhibitory activity and show that the most purified preparation of E2F-I contains a 105 kd E1A-binding protein. This 105 kd E1A-binding protein cross-reacts with two different antibodies against the retinoblastoma (RB) gene product. Moreover, the RB gene product copurifies with E2F-I activity. Taken together, we conclude that the product of the RB gene is a part of E2F-I and is involved in the regulation of E2F activity.
Bagchi
S
S
Department of Biochemistry (M/C 536), College of Dentistry (M/C 860), University of Illinois, Chicago 60680.
Weinmann
R
R
Raychaudhuri
P
P
D017456:Adenovirus Early Proteins; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000302:isolation & purification; D050684:E2F Transcription Factors; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009841:Oligonucleotides / Q000737:chemistry; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D016160:Retinoblastoma Protein / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D014158:Transcription, Genetic
D017456:Adenovirus Early Proteins; C533431:Arid4a protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D046911:Macromolecular Substances; D009841:Oligonucleotides; D009856:Oncogene Proteins, Viral; D016160:Retinoblastoma Protein; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors