Eukaryotic DNA replication origins are selected in G1-phase when the origin recognition complex (ORC) binds chromosomal positions and triggers molecular events culminating in the initiation of DNA replication (a.k.a. origin firing) during S-phase. Each chromosome uses multiple origins for its duplication, and each origin fires at a characteristic time during S-phase, creating a cell-type specif...

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The Origin Recognition Complex (ORC) is a six-protein assembly that specifies the sites of DNA replication initiation in S. cerevisiae. Origin recognition by ORC requires ATP. Here, we demonstrate that two subunits, Orc1p and Orc5p, bind ATP and that Orc1p also hydrolyzes ATP. ATP binding and hydrolysis by Orc1p are both regulated by origin DNA in a sequence-specific manner. ATP binding to Orc1...

The origin recognition complex (ORC) was initially discovered in budding yeast extracts as a protein complex that binds with high affinity to autonomously replicating sequences in an ATP-dependent manner. We have cloned and expressed the human homologs of the ORC subunits as recombinant proteins. In contrast to other eukaryotic initiators examined thus far, assembly of human ORC in vitro is dep...

Accurate DNA replication requires proper regulation of replication licensing, which entails loading MCM-2-7 onto replication origins. In this paper, we provide the first comprehensive view of replication licensing in vivo, using video microscopy of Caenorhabditis elegans embryos. As expected, MCM-2-7 loading in late M phase depended on the prereplicative complex (pre-RC) proteins: origin recogn...

Initiation of eukaryotic genome duplication begins when a six-subunit origin recognition complex (ORC) binds to DNA. However, the mechanism by which this occurs in vivo and the roles played by individual subunits appear to differ significantly among organisms. Previous studies identified a soluble human ORC(2-5) complex in the nucleus, an ORC(1-5) complex bound to chromatin, and an Orc6 protein...

Orc is a theory of orchestration of services that allows structured programming of distributed and timed computations. Several formal semantics have been proposed for Orc, including a rewriting logic semantics developed by the authors. Orc also has a fully fledged implementation in Java with functional programming features. However, as with descriptions of most distributed languages, there exis...

In the quest to define autonomously replicating sequences (ARSs) in eukaryotic cells, an ARS consensus sequence (ACS) has emerged for budding yeast. This ACS is recognized by the replication initiator, the origin recognition complex (ORC). However, not every match to the ACS constitutes a replication origin. Here, we investigated the requirements for ORC binding to origins that carry multiple, ...

In this study we investigated how hemostats such as oxidized regenerated cellulose (ORC, TABOTAMP) and oxidized non-regenerated cellulose (ONRC, RESORBA CELL) influence local cellular behavior and contraction of the extracellular matrix (ECM). Human stromal fibroblasts were inoculated in vitro with ORC and ONRC. Cell proliferation was assayed over time, and migration was evaluated by Live Cell ...

DNA replication initiates by formation of a pre-replication complex on sequences termed origins. In eukaryotes, the pre-replication complex is composed of the Origin Recognition Complex (ORC), Cdc6 and the MCM replicative helicase in conjunction with Cdt1. Eukaryotic ORC is considered to be composed of six subunits, named Orc1-6, and monomeric Cdc6 is closely related in sequence to Orc1. Howeve...