Interaction between the origin recognition complex and the replication licensing system in Xenopus

Alison Rowles, James P. J. Chong, Lamorna Brown, Mike Howell, Gerard I. Evan, J. Julian Blow

Research output: Contribution to journalArticlepeer-review


The origin recognition complex (ORC) binds to origins of replication in budding yeast. We have cloned a Xenopus homolog of the largest ORC polypeptide (XORC1). Immunodepletion of XOrc1 from Xenopus egg extracts blocks the initiation of DNA replication. We have purified Xenopus ORC, consisting of a protein complex similar to yeast ORC. In Xenopus egg extracts, ORC associates with chromatin throughout G1 and S phases. RLF-M, a component of the replication licensing system, also associates with chromatin early in the cell cycle but dissociates during S phase. We show that the assembly of RLF-M onto chromatin is dependent on the presence of chromatin-bound ORC, leading to sequential assembly of initiation proteins onto replication origins during the cell cycle.
Original languageEnglish
Pages (from-to)287-296
Number of pages10
Issue number2
Publication statusPublished - 18 Oct 1996

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