E2F-1-MEDIATED TRANSACTIVATION IS INHIBITED BY COMPLEX-FORMATION WITH THE RETINOBLASTOMA SUSCEPTIBILITY GENE-PRODUCT
E2F-1-MEDIATED TRANSACTIVATION IS INHIBITED BY COMPLEX-FORMATION WITH THE RETINOBLASTOMA SUSCEPTIBILITY GENE-PRODUCT
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DOI：
10.1073/pnas.90.15.6914
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发表时间：
1993-08-01
影响因子：
11.1
通讯作者：
KAELIN, WG
中科院分区：
文献类型：
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作者：
FLEMINGTON, EK;SPECK, SH;KAELIN, WG
先前的研究表明，E2 F-1的羧基末端区域（残基368-437）可以支持转录激活时，连接到酵母转录因子GAL 4的DNA结合结构域。该区域还包含一个18个残基的视网膜母细胞瘤（RB）结合序列，增加了RB结合可能抑制E2 F-1形成激活所需的蛋白质-蛋白质接触的能力的可能性。在这里，我们报告了E2 F-1激活域的进一步分析。此外，我们发现RB的过表达，而不是RB突变体，RBd 22，可以抑制GAL 4/E2 F-1的活性在体内。此外，猴病毒40大肿瘤抗原（T抗原）的表达，而不是RB结合缺陷的T抗原点突变体，K1，可以克服这种抑制。三种不同的GAL 4/E2 F-1突变体激活转录，但不能结合RB，不受RB过表达的显着影响。这些发现支持RB通过直接物理结合抑制E2 F-1介导的转录激活的模型。
Previous studies have shown that the carboxyl-terminal region of E2F-1 (residues 368-437) can support transcriptional activation when linked to the DNA-binding domain of the yeast transcription factor GAL4. This region also contains an 18-residue retinoblastoma (RB)-binding sequence, raising the possibility that RB binding might inhibit the ability of E2F-1 to form protein-protein contacts required for activation. Here we report a further analysis of the E2F-1 activation domain. In addition, we show that overexpression of RB, but not the RB mutant, RBd22, can inhibit GAL4/E2F-1 activity in vivo. Moreover, expression of the simian virus 40 large tumor antigen (T antigen), but not the RB-binding defective T antigen point mutant, K1, can overcome this repression. Three different GAL4/E2F-1 mutants that activate transcription, but fail to bind to RB, are not significantly affected by overexpression of RB. These findings support a model wherein RB suppresses E2F-1-mediated transcriptional activation through direct physical association.