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The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
The cell cycle is driven by proteins called cyclin dependent kinases that associate with cyclin regulatory proteins at different checkpoints of the cell cycle. Different phases of the cell cycle experience activation and/or deactivation of specific cyclin-CDK complexes. CyclinB-CDK1 activity is specific to the G2/M checkpoint.
Proteases prevent this cycle from occurring by altering the rate of one of the pathways, or by cleaving a key enzyme, they can stop one of the pathways. Proteases are also nonspecific when binding to substrate , allowing for great amounts of diversity inside the cells and other proteins, as they can be cleaved much easier in an energy efficient ...
The main mechanism of action of the cell cycle checkpoints is through the regulation of the activities of a family of protein kinases known as the cyclin-dependent kinases (CDKs), which bind to different classes of regulator proteins known as cyclins, with specific cyclin-CDK complexes being formed and activated at different phases of the cell ...
Bottom, signal enters the cell nucleus and causes transcription of DNA, which is then expressed as protein. The MAPK/ERK pathway (also known as the Ras-Raf-MEK-ERK pathway) is a chain of proteins in the cell that communicates a signal from a receptor on the surface of the cell to the DNA in the nucleus of the cell.
In cell biology, a biological pathway is a series of interactions among molecules in a cell that leads to a certain product or a change in the cell. Such a pathway can trigger the assembly of new molecules, such as a fat or protein. Pathways can also turn genes on and off, or spur a cell to move. [1]
For example, Cdk, or cyclin dependent kinase, is a major control switch for the cell cycle and it allows the cell to move from G1 to S or G2 to M by adding phosphate to protein substrates. Such multi-component (involving multiple inter-linked proteins) switches have been shown to generate decisive, robust (and potentially irreversible ...
Cell division control protein 42 homolog (Cdc42 or CDC42) is a protein that in humans is encoded by the CDC42 gene. Cdc42 is involved in regulation of the cell cycle.It was originally identified in S. cerevisiae (yeast) as a mediator of cell division, [5] [6] and is now known to influence a variety of signaling events and cellular processes in a variety of organisms from yeast to mammals.