Arroyo M, Raychaudhuri P
Department of Biochemistry, University of Illinois, Chicago 60680.
Nucleic Acids Res. 1992 Nov 25;20(22):5947-54. doi: 10.1093/nar/20.22.5947.
The product of the retinoblastoma tumor suppressor gene interacts with the transcription factor E2F. Two distinct types of interactions can be detected between the retinoblastoma gene product (Rb) and E2F. The first type involves an Rb-binding protein, RBP60. The Rb/E2F complex formed in the presence of RBP60 is able to bind DNA and migrates with a distinct mobility in gel retardation assays. The second type of Rb/E2F complex is seen in the absence of RBP60. This second type of Rb/E2F complex does not form a band-shift complex in gel retardation assays and its formation results in an apparent inhibition or loss of the DNA binding activity of E2F. Using a series of Rb-mutants we show that these two types of Rb/E2F complexes depend on common domains of the Rb protein. The T/E1A-binding region as well as the carboxyl-terminus of the Rb protein are critical for these two types of Rb/E2F interactions. We also show that the retinoblastoma protein represses the E2F-dependent transcription, and this Rb-repression of the E2F-dependent transcription depends on the ability of Rb to interact with E2F. Moreover, the adenovirus E1A gene product, which binds Rb, counteracts the Rb-repression and restores E2F-dependent transcription.
视网膜母细胞瘤抑癌基因的产物与转录因子E2F相互作用。在视网膜母细胞瘤基因产物（Rb）和E2F之间可检测到两种不同类型的相互作用。第一种类型涉及一种Rb结合蛋白RBP60。在RBP60存在的情况下形成的Rb/E2F复合物能够结合DNA，并在凝胶阻滞试验中以独特的迁移率迁移。第二种类型的Rb/E2F复合物在没有RBP60的情况下可见。这种第二种类型的Rb/E2F复合物在凝胶阻滞试验中不形成条带迁移复合物，其形成导致E2F的DNA结合活性明显受到抑制或丧失。使用一系列Rb突变体，我们表明这两种类型的Rb/E2F复合物依赖于Rb蛋白的共同结构域。Rb蛋白的T/E1A结合区域以及羧基末端对于这两种类型的Rb/E2F相互作用至关重要。我们还表明，视网膜母细胞瘤蛋白抑制E2F依赖的转录，并且Rb对E2F依赖转录的这种抑制取决于Rb与E2F相互作用的能力。此外，与Rb结合的腺病毒E1A基因产物可抵消Rb的抑制作用并恢复E2F依赖的转录。
