Protein phosphorylation

Protein phosphorylation -...

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Protein phosphorylation, a common mode of regulation in cells, is a major mechanism of signal  transduction. The phosphorylation of proteins by a specific enzyme (a  protein kinase ) is a widespread  cellular mechanism for regulating protein activity. Most protein kinases act on other substrate proteins, unlike tyrosine kinases, which act on  themselves. Most phosphorylation occurs at either serine or threonine amino acids of the substrate protein  (unlike tyrosine phosphorylation in tyrosine kinases). Many of the relay molecules in a signal transduction pathway are protein kinases that act on  other protein kinases to create a “phosphorylation cascade.” Each protein phosphorylation leads to a conformational change because of the interaction  between the newly added phosphate group and charged or polar amino acids on the protein. Phosphorylation of a protein typically converts it from an inactive form to an active form. o Only rarely does phosphorylation  decreases  the activity of the protein. A single cell may have hundreds of different protein kinases, each specific for a different  substrate protein. o Fully 2% of our genes are thought to code for protein kinases. o Together, they regulate a large proportion of the thousands of the proteins in a cell. Abnormal activity of protein kinases can cause abnormal cell growth and may contribute to the  development of cancer.
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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Protein phosphorylation -...

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