What is the function of Cdc6 and Cdt1 in DNA replication?
Pre-replication complex formation establishes replication competence before S phase, separating helicase loading from activation. Origin recognition complex ORC marks replication origins throughout cell cycle at AT-rich sequences. In late mitosis and early G1 when CDK activity minimal due to APC/C-Cdh1 mediated cyclin degradation, AAA+ ATPase Cdc6 binds ORC and recruits chaperone Cdt1 bound to single hexamer of MCM2-7 helicase. ATP hydrolysis by Cdc6 and ORC opens MCM ring, allowing encirclement of double-stranded DNA and formation of inactive double hexamer encircling DNA in head-to-head orie
Ref: Bell & Labib, Genes & Dev 2016, Pre-RC Assembly. Alberts 7th ed., Chapter 5, Replication Licensing.
