Perkins G, Diffley J F
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, United Kingdom.
Mol Cell. 1998 Jul;2(1):23-32. doi: 10.1016/s1097-2765(00)80110-0.
Expression of the Cdc6 protein (Cdc6p) is essential for formation of prereplicative complexes at budding yeast replication origins. Analysis of mutations in the conserved nucleoside triphosphate (NTP)-binding site of Cdc6p described here suggests that NTPs are required both for the productive interaction of Cdc6p with replication origins during G1 and the quantitative loading of the Mcm2-7 family of proteins onto chromatin. We show that Cdc6p exhibits significant sequence similarity to subunits of eukaryotic and prokaryotic clamp-loaders, which load ring-shaped DNA polymerase processivity factors onto DNA in an analogous reaction. Similarities in both sequence and mechanism suggest that Cdc6p and the clamp-loaders are members of a superfamily of nucleotide-dependent loading factors.
Cdc6蛋白（Cdc6p）的表达对于芽殖酵母复制起点处前复制复合物的形成至关重要。本文对Cdc6p保守的核苷三磷酸（NTP）结合位点突变的分析表明，NTPs对于G1期Cdc6p与复制起点的有效相互作用以及Mcm2-7蛋白家族在染色质上的定量装载都是必需的。我们发现Cdc6p与真核和原核钳式装载蛋白的亚基具有显著的序列相似性，这些钳式装载蛋白在类似反应中将环形DNA聚合酶持续性因子装载到DNA上。序列和机制上的相似性表明，Cdc6p和钳式装载蛋白是核苷酸依赖性装载因子超家族的成员。
