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Searched for: REACTOME AND Orc1 removal from chromatin [All Organisms, All Data Sources]

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Pathways (5)Molecules (4)
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Pathway: Orc1 removal from chromatin  from Reactome  [98 molecules]
  • ... Orc1 removal from chromatin ...
  • ... Reactome ...
  • ... reactome.
  • Mammalian Orc1 protein is selectively released from chromatin and ubiquitinated during the S-to-M transition.
  • ... Reactome stable identifier.
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Pathway: Assembly of the ORC complex at the origin of replication  from Reactome  [13 molecules]
In Saccharomyces cerevisiae, the entire ORC complex is constitutively bound to the origin of replication.

Summary:  In Saccharomyces cerevisiae, the entire ORC complex is constitutively bound to the origin of replication. However, in mammalian cells, Orc1, and possibly other Orc subunits, dissociate from origins of replication, while Orc2 remains stably associated with chromatin across the cell cycle. The first step in formation of the pre-RC is assembly of the hexameric Origin Recognition Complex (ORC) at the origin of replication. Recent work on human (Hs) ORC has suggested that the heterohexamer assembles in an ordered manner. HsOrc2 appears to be constitutively bound to origins of replication. HsOrc2 and HsOrc3 form a complex that interacts with HsOrc4 and HsOrc5. Recruitment of HsOrc5 into the complex is important for the association of HsOrc1. HsOrc6 is also capable of interacting with the core HsOrc2:3:4:5 complex, but not smaller complexes. Interestingly, HsOrc1 and a subunit of the Mcm2-7 complex (HsMcm2) interact with a histone acetyltransferase, HsHBO1 (Bell & Stillman 1992; Diffley et al. 1994; Lee & Bell 1997; Wenger et al. 1975; Li & DePamphili;s 2001; Dhar et al. 2001; Vashee et al, 2001; Iizuka & Stillman 1999 Burke et al. 2001).

  • ... However, in mammalian cells, Orc1, and possibly other Orc subunits, dissociate from origins of replication, while Orc2 remains stably associated with chromatin.
  • Mammalian Orc1 protein is selectively released from chromatin and ubiquitinated during the S-to-M transition in the cell division cycle.
  • ... Reactome ...
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Pathway: Assembly of the pre-replicative complex  from Reactome  [97 molecules]
Authored: Davey, MJ, O'Donnell, M, Tye, BK, 2006-03-17 16:01:39.

Summary:  Authored: Davey, MJ, O'Donnell, M, Tye, BK, 2006-03-17 16:01:39

  • ... and chromatin-bound MCM proteins during the cell cycle in cdc6 mutants.
  • ... Reactome.
  • ... Reactome ...
  • ... reactome.
  • ... cerevisiae/i and humans has been demonstrated by chromatin immunoprecipitation experiments. ... cerevisiae/i, pre-replicative complexes are assembled from late M to G1. ... In mammalian cells as well, pre-replicative complexes are assembled from late M to G1, as shown ...
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Pathway: CDC6 association with the ORC:origin complex  from Reactome  [13 molecules]
Authored: Davey, MJ, O'Donnell, M, Tye, BK, 2006-03-17 16:01:39.

Summary:  Authored: Davey, MJ, O'Donnell, M, Tye, BK, 2006-03-17 16:01:39

  • ... associates with Orc1 and cyclin-cdk and is selectively eliminated from the nucleus at the onset of S.
  • ... Reactome ...
  • ... reactome. ... have suggested that after cells enter S phase, Cdc6 is phosphorylated, excluded from the nucleus. ... to the web page of this instance in Reactome: http://www. ...reactome.
  • ... REACTOME DATABASE ID ...
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Pathway: Activation of the pre-replicative complex  from Reactome  [55 molecules]
In S.

Summary:  In S. cerevisiae, two ORC subunits, Orc1 and Orc5, both bind ATP, and Orc1 in addition has ATPase activity. Both ATP binding and ATP hydrolysis appear to be essential functions in vivo. ATP binding by Orc1 is unaffected by the association of ORC with origin DNA (ARS) sequences, but ATP hydrolysis is ARS-dependent, being suppressed by associated double-stranded DNA and stimulated by associated single-stranded DNA. These data are consistent with the hypothesis that ORC functions as an ATPase switch, hydrolyzing bound ATP and changing state as DNA unwinds at the origin immediately before replication. It is attractive to speculate that ORC likewise functions as a switch as human pre-replicative complexes are activated, but human Orc proteins are not well enough characterized to allow the model to be critically tested. mRNAs encoding human orthologs of all six Orc proteins have been cloned, and ATP-binding amino acid sequence motifs have been identified in Orc1, Orc4, and Orc5. Interactions among proteins expressed from the cloned genes have been characterized, but the ATP-binding and hydrolyzing properties of these proteins and complexes of them have not been determined.

  • ... Reactome ...
  • ... reactome. ... cerevisiae, two ORC subunits, Orc1 and Orc5, both bind ATP, and Orc1 in addition has ATPase. ... by Orc1 is unaffected by the association of ORC with origin DNA (ARS) sequences, but ATP hydrolysis. ..., and ATP-binding amino acid sequence motifs have been identified in Orc1, Orc4, and Orc5. ... Interactions among proteins expressed from the cloned genes have been characterized, but the ATP-binding ...