Year-end Sale % OFF 
Abstract
The interaction of the origin recognition complex (ORC) with replication origins is a critical parameter in eukaryotic replication initiation. In mammals the ORC remains bound except during mitosis, thus the localization of ORC complexes allows localization of origins. A monoclonal antibody that recognizes human ORC1 was used to localize ORC complexes in populations of human MOLT-4 cells separated by cell cycle position using centrifugal elutriation. ORC1 staining in cells in early G1 is diffuse and primarily peripheral. As the cells traverse G1, ORC1 accumulates and becomes more localized towards the center of the nucleus, however around the G1/S boundary the staining pattern changes and ORC1 appears peripheral. By mid to late S phase ORC1 immunofluorescence is again concentrated at the nuclear center. During anaphase, ORC1 staining is localized mainly in the pericentriolar regions. These findings suggest that concerted movements of origin DNA sequences in addition to the previously documented assembly and disassembly of protein complexes are an important aspect of replication initiation loci in eukaryotes.
Highlights
In mammalian cells, the initiation of DNA replication appears to occur in close proximity to the nuclear matrix [1, 3, 8, 17, 23, 25]
ORC1 staining is localized mainly in the pericentriolar regions. These findings suggest that concerted movements of origin DNA sequences in addition to the previously documented assembly and disassembly of protein complexes are an important aspect of replication initiation loci in eukaryotes
As cells progress through G1, the ORC1 immunofluorescence diminishes at the nuclear periphery and increases at the center of the nucleus, until by late G1 virtually all immunofluorescence is seen at the nuclear center (Fig. 3C)
Summary
The initiation of DNA replication appears to occur in close proximity to the nuclear matrix [1, 3, 8, 17, 23, 25]. The six proteins of the origin recognition complex (ORC) and the MCM proteins bind to origin sequences throughout the cell cycle [19, 28, 33]. These complexes sequentially recruit a series of proteins that result in a particular replication initiation site being opened by the MCM helicase activity and bound by the replicative polymerases.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
