Interaction Between the Origin Recognition Complex and the Replication Licensing System in Xenopus

Cell. 1996 Oct 18;87(2):287-96. doi: 10.1016/s0092-8674(00)81346-x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Cycle
  • Cell-Free System
  • Chromatin / metabolism
  • Chromatin / ultrastructure
  • Cloning, Molecular
  • DNA Replication*
  • DNA-Binding Proteins / physiology*
  • Humans
  • Immunologic Techniques
  • Male
  • Molecular Sequence Data
  • Oocytes
  • Origin Recognition Complex
  • Sequence Alignment
  • Spermatozoa
  • Xenopus Proteins*
  • Xenopus laevis / genetics*


  • Chromatin
  • DNA-Binding Proteins
  • Origin Recognition Complex
  • XOrc1 protein, Xenopus
  • Xenopus Proteins

Associated data

  • GENBANK/U67190