| 1995 |
ORC3 (62 kDa subunit) is one of the six subunits of the origin recognition complex (ORC); all six subunits were reconstituted as a complete complex after expression in insect cells, establishing ORC3 as a core structural component of the replication initiator. |
Recombinant protein expression in insect cells and complex reconstitution |
Cell |
High |
7585959
|
| 1999 |
Drosophila Latheo (ORC3 ortholog) associates with ORC2 and is functionally related to yeast ORC3, establishing that LAT/ORC3 is a conserved subunit required for DNA replication and cell proliferation; homozygous lethal lat mutants show absence of imaginal discs and lack CNS cell proliferation, rescued by a lat+ transgene. |
Co-immunoprecipitation, transgene rescue, genetic analysis of lethal mutants |
Neuron |
High |
10402192
|
| 1999 |
Drosophila LAT (ORC3 ortholog) protein localizes to synaptic connections at the larval NMJ and is enriched in presynaptic boutons; lat mutants show elevated basal synaptic transmission and loss of Ca2+-dependent synaptic facilitation and posttetanic potentiation. |
Immunological localization, electrophysiological recordings at NMJ in lat mutants |
Neuron |
Medium |
10402193
|
| 2000 |
Human ORC2, ORC3, and ORC5 are detected in non-proliferating cells (cardiac myocytes, adrenal cortical cells, neurons), suggesting ORC3 functions outside of its role in DNA replication initiation; ORC2-5 co-immunoprecipitate under mild but not stringent extraction conditions, and ORC3 under stringent conditions associates with unidentified non-ORC proteins. |
Co-immunoprecipitation under varying extraction conditions, immunohistochemistry in tissue |
The Journal of biological chemistry |
Medium |
10954718
|
| 2007 |
Human ORC6 binds directly to ORC3 and interacts as part of ORC in vivo; immunoprecipitation shows ORC disassembles as cells progress through S phase; anti-Orc3 immunofluorescence shows cell cycle-dependent association with a nuclear structure. |
Immunoprecipitation, immunofluorescence staining, recombinant protein expression |
The Journal of biological chemistry |
Medium |
17716973
|
| 2008 |
In the S. cerevisiae ORC structure determined by single-particle EM, subunits are arranged as Orc1:Orc4:Orc5:Orc2:Orc3, with Orc6 localized near Orc2 and Orc3; subunit-subunit interactions confirmed by in vitro immunoprecipitation of subunits synthesized in vitro. |
Single-particle electron microscopy, MBP-fusion tag localization, in vitro immunoprecipitation |
Proceedings of the National Academy of Sciences of the United States of America |
High |
18647841
|
| 2010 |
Human ORC3 directly binds HP1alpha; two independent domains of ORC3 (a coiled-coil domain and a mod-interacting region domain) can each independently bind HP1alpha, but both are required together for in vivo localization of ORC3 to heterochromatic foci; depletion of ORC3 by siRNA causes loss of HP1alpha association to heterochromatin and loss of compaction at satellite repeats. |
Direct binding assays, fluorescence microscopy, siRNA knockdown, FRAP |
Proceedings of the National Academy of Sciences of the United States of America |
High |
20689044
|
| 2012 |
In the cryo-EM structure of S. cerevisiae ORC-Cdc6-DNA, the six ORC subunits are arranged as Orc1:Orc4:Orc5:Orc2:Orc3 with Orc6 binding to Orc2; the complex bends and wraps origin DNA along the interior crescent surface; Cdc6 binding reorients the Orc1 N-terminal BAH domain. |
Single-particle cryo-electron microscopy, 3D reconstruction, docking with archaeal crystal structure |
Structure |
High |
22405012
|
| 2012 |
Conditional deletion of orc3 from glial progenitors in mouse dramatically reduces glial progenitor cell number in the subventricular zone and astrocytes in the postnatal cortex, demonstrating that ORC3 is required for DNA replication-dependent glial progenitor proliferation; loss of astroglia secondarily impairs cortical blood vessel density and branching. |
Conditional genetic knockout in mouse, histological and immunofluorescence analysis of cortex and vasculature |
PloS one |
Medium |
23110156
|
| 2013 |
A Meier-Gorlin syndrome mutation in the Orc6 C-terminus impedes its recruitment into ORC by disrupting binding to a previously uncharacterized domain of ORC3; this Orc6-Orc3 interaction is required for ORC function and MCM2-7 loading in vivo. |
3D electron microscopy of metazoan ORC, biochemical binding assays, in vivo functional assays |
eLife |
High |
24137536
|
| 2007 |
ORC2 and ORC3 interact in live mammalian cells not only in the nucleus but also in the cytoplasm, as demonstrated by BRET and BiFC assays; NLS-depleted ORC3 still interacts with ORC2, indicating the interaction is not restricted to nuclear localization. |
Bioluminescence resonance energy transfer (BRET), bimolecular fluorescence complementation (BiFC) in live cells |
Molecular genetics and genomics |
Medium |
17680271
|
| 2014 |
Phosphorylation of ORC2 by cyclin A/CDK2 during S phase leads to dissociation of ORC2, ORC3, ORC4, and ORC5 from human chromatin and replication origins; PP1 dephosphorylates ORC2 via the consensus motif 119-KSVSF-123, and this dephosphorylation is required for re-binding of these subunits (including ORC3) to chromatin. |
Co-immunoprecipitation, chromatin fractionation, PP1 inhibitor treatment, PP1 isoform overexpression and siRNA knockdown |
Biochemical and biophysical research communications |
Medium |
24732362 24792176
|
| 2019 |
The ubiquitin ligase OBI1 (C13ORF7/RNF219) catalyzes multi-mono-ubiquitylation of chromatin-bound ORC3 (and ORC5) during S phase; expression of non-ubiquitylable ORC3/5 mutants impairs origin firing without affecting pre-RC establishment, identifying ORC3 ubiquitylation as a signal required for replication origin activation. |
Proteomic interactome of pre-RC, ubiquitylation assays, CMG formation assay, origin firing analysis with non-ubiquitylable mutants |
Nature communications |
High |
31160578
|
| 2020 |
Five cryo-EM structures of human ORC reveal that ORC2-5 forms a compact stable core; introduction of ORC1 opens the complex into dynamic conformations; a hinge at the ORC5·ORC3 interface mediates twist and pinch motions in an open ORC conformation that may facilitate DNA binding. |
Single-particle cryo-electron microscopy, five independent structures |
eLife |
High |
32808929
|
| 2010 |
In cultured cerebellar granule cells (CGCs), ORC3 knockdown by siRNA reduces expression of neuronal maturation markers MAP-2 and PSD-95 and increases active GTP-bound Rho, while mGlu4 receptor activation increases ORC3 and reduces Rho activation; these effects are abrogated by ORC3 siRNA, indicating ORC3 supports neuronal maturation by inhibiting the Rho signaling pathway. |
siRNA knockdown, western blot for MAP-2/PSD-95/active Rho, pharmacological manipulation of mGlu4 receptors |
Brain research |
Medium |
20674557
|
| 2016 |
Drosophila ORC (including Orc3) physically interacts with the THSC/TREX-2 mRNA nuclear export complex; Orc3 knockdown increases the level of mRNP-bound Nxf1 and causes nuclear mRNA accumulation, indicating ORC3 participates in regulating mRNP export. |
Biochemical purification from Drosophila embryo extract, Co-IP, RNAi knockdown with nuclear mRNA accumulation assay |
Nucleic acids research |
Medium |
27016737
|
| 2021 |
In Drosophila, the TREX-2 platform protein Xmas-2 interacts with Orc3 through its C-terminal region downstream of the CID domain, defining the molecular interface of the TREX-2-ORC interaction. |
Deletion mapping of Xmas-2 interaction domains with Orc3 by pulldown/co-IP |
Doklady. Biochemistry and biophysics |
Low |
33689068
|
| 2023 |
The human TREX-2-ORC joint complex is formed in human cells, extending the Drosophila finding; ORC3 is implicated as part of this interaction. |
Co-immunoprecipitation in human cells |
Doklady. Biochemistry and biophysics |
Low |
38066323
|
| 2024 |
Biochemical reconstitution of human MCM loading shows that ORC6 and ORC3 facilitate ORC recruitment to the dimerization interface of the first MCM hexamer to form MCM-ORC (MO) complexes; ORC3 contributes an element (the ORC3 tether) that supports an ORC6-independent MCM loading mechanism, and both ORC6 and ORC3 orient ORC for second MCM hexamer loading. |
Biochemical reconstitution of human MCM loading, electron microscopy of loading intermediates |
Nature |
High |
39604729
|
| 2025 |
A cryo-EM structure of an ORC-Cdc6-Cdt1-MCM2-7 intermediate shows that the Mcm5 C-terminus contacts ORC3 and specifically recognizes the closed MCM2/Mcm5 ring interface, linking ORC3 to a step in pre-RC assembly that triggers Mcm4 ATP hydrolysis and Cdt1 release. |
Cryo-EM structure determination, mutagenesis of Mcm2/Mcm5 interface, helicase loading assays |
Nature communications |
High |
39747125
|
| 2025 |
AlphaFold-guided phylogenetic analysis reveals that ORC3 contains an 'ORC3 tether' element that interacts with MCM to facilitate ORC6-independent MCM loading, and this element is broadly conserved across Metazoa even in lineages that have lost ORC6. |
AlphaFold2 Multimer structural predictions, phylogenetic analysis across metazoan lineages |
The EMBO journal |
Low |
41310087
|