PräReplikationskomplex

The PräReplikationskomplex, often abbreviated as pre-RC, is a multiprotein complex that assembles at replication origins in eukaryotic cells prior to the initiation of DNA replication. Its formation is a crucial step in ensuring that DNA replication occurs only once per cell cycle and at the correct time. The pre-RC is composed of several key components, including the Origin Recognition Complex (ORC), Cdc6, and the mini-chromosome maintenance (MCM) helicase complex. ORC binds to specific DNA sequences at replication origins, acting as a landing pad for other pre-RC factors. Cdc6 then recruits the MCM complex to the origin. The MCM complex is the core of the replicative helicase, responsible for unwinding the DNA double helix to allow replication forks to proceed. The assembly of the pre-RC is tightly regulated by cell cycle control mechanisms. It forms during the G1 phase of the cell cycle and remains inactive until the S phase, when it is activated by cyclin-dependent kinases (CDKs) and other signaling pathways. This temporal regulation prevents premature or re-replication of the genome. The formation and activation of the pre-RC are fundamental to maintaining genomic stability and ensuring accurate DNA duplication. Disruptions in pre-RC assembly or function can lead to genomic instability and are implicated in various diseases, including cancer.