Sterner J M, Dew-Knight S, Musahl C, Kornbluth S, Horowitz J M
Department of Molecular Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Mol Cell Biol. 1998 May;18(5):2748-57. doi: 10.1128/MCB.18.5.2748.
A yeast two-hybrid screen was employed to identify human proteins that specifically bind the amino-terminal 400 amino acids of the retinoblastoma (Rb) protein. Two independent cDNAs resulting from this screen were found to encode the carboxy-terminal 137 amino acids of MCM7, a member of a family of proteins that comprise replication licensing factor. Full-length Rb and MCM7 form protein complexes in vitro, and the amino termini of two Rb-related proteins, p107 and p130, also bind MCM7. Protein complexes between Rb and MCM7 were also detected in anti-Rb immunoprecipitates prepared from human cells. The amino-termini of Rb and p130 strongly inhibited DNA replication in an MCM7-dependent fashion in a Xenopus in vitro DNA replication assay system. These data provide the first evidence that Rb and Rb-related proteins can directly regulate DNA replication and that components of licensing factor are targets of the products of tumor suppressor genes.
采用酵母双杂交筛选来鉴定与视网膜母细胞瘤（Rb）蛋白氨基末端400个氨基酸特异性结合的人类蛋白质。该筛选得到的两个独立cDNA被发现编码MCM7的羧基末端137个氨基酸，MCM7是包含复制许可因子的蛋白质家族的成员。全长Rb和MCM7在体外形成蛋白质复合物，并且两个Rb相关蛋白p107和p130的氨基末端也与MCM7结合。在从人类细胞制备的抗Rb免疫沉淀中也检测到Rb和MCM7之间的蛋白质复合物。在非洲爪蟾体外DNA复制测定系统中，Rb和p130的氨基末端以MCM7依赖的方式强烈抑制DNA复制。这些数据首次证明Rb和Rb相关蛋白可以直接调节DNA复制，并且许可因子的成分是肿瘤抑制基因产物的靶标。
