The regular mechanism of eukaryotic DNA replication Abstract: 1、conserved initiator,divergent replicator 2、the origin recognition system 3、replication licensing system 4、SPF 3th group:罗通 郭鹏 杨孔
Conserved intiator,divergent replicator
Xenopus eggs and egg extracts Three distinct system: the origin recognition system(ORC) the replication licensing system S phase-promoting factor ,SPF (Cdc7,CDKs)
the origin recognition system(ORC) In the early Xenopus embryo, replication origins are positioned randomly with respect to DNA sequence then,origins become restricted to specific DNA seqences. It seem likely that The periodic spacing of replication origins is mediated by periodic binding of ORC along the chromosomal DNA. Two different model of periodic spacing of ORC.
replication licensing system 复制认证系统的组成: Fig.4认证模式的必需组件。起点的认证通过 起点结合Mcm(2-7)蛋白实现的。Mcm(2-7)是必须的,但其功能不清楚。可能是起解旋酶的作用。 认证系统的启动时间和抑制时间:Cdt1、Cdc6结合到起点认证开始,S期开始前受到抑制。 认证系统的调控和作用。Fig-5。 认证系统的沉默受到多重调节(1、2、3、RLF-B/Cdt1抑制子,S、G2期积累,中后期转换时突然降解,此时认证系统被启动)。
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四、SPF SPF的组成:Cdc7和CDK s(周期依赖蛋 白激酶)。 Cdc7在减数分裂末到S期末召募到已被认证的染色体上。 CDKs:B,A, E . SPF的调控和作用:不依赖周期蛋白的丰富程度和核的超级结构,可能是由于Cdk-cyclin E功能的全部启动依赖与 Cdc34 介导的蛋白水解作用,这种水解作用只能在核质中启动。 SPF的抑制时间:在减数分裂晚期和G1期受到抑制。
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