Posttranslational Control These mechanisms act after the protein has been produced. Protein Activation Some proteins are not active when they are first formed. They must undergo modification such as folding, enzymatic cleavage, or bond formation. Example: Proinsulin is a precursor to the hormone insulin. It must be cleaved into 2 polypeptide chains and then some amino acids must be removed to form insulin. Many proteins are activated by adding phosphate groups. They can be inactivated by removing phosphate groups. For example, kinases activate by adding phosphate groups and phosphodiesterase inactivates by removing the phosphate groups. Feedback Control Some enzymes in a metabolic pathway may be negatively inhibited by products of the pathway. Click here form more details on feedback control. Modification of DNA Gene Amplification In Drosophila (fruit flies), the chorion (eggshell) gene is copied many times in certain cells of the oviduct. These cells make large quantities of the protein needed to surround the egg. In other
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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.