Adenoviruses and cytomegalo virus use to reduce the surface expression of class I MHC molecules, 

Measles virus and HIV, reduce levels of class II MHC molecules on the surface, 

Vaccinia virus, secreting a protein that binds to the C4b complement component.

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#Unit 3. Fundamental Processes

The striking feature is that ORC remains bound at the origin through the entire cell Cycle.

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#Id: 2964

#Unit 3. Fundamental Processes

The major role of ORC is to identify the origin to the Cdc6 and MCM proteins that control initiation and licensing.

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#Unit 3. Fundamental Processes

In yeast, Cdc6 is a highly unstable protein, with a half-life of <5 minutes. It is synthesized during G1 and typically binds to ORC between the exit from mitosis and late G1.

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#Unit 3. Fundamental Processes

pathway. Cdt1  is initially stabilized by the protein Geminin, which prevents its degradation, and subsequent Geminin binding prevents its reuse.

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#Unit 3. Fundamental Processes

In yeast, the replication helicase MCM2-7 (minichromosome maintenance) complex enters the nucleus as an inactive double hexamer during mitosis.

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#Unit 3. Fundamental Processes

The presence of Cdc6 and Cdtl at the yeast origin allows the MCM proteins to bind to the complex in G I in the inactive state. Their presence is necessary forinitiation.