Post-translational modifications mechanism

A wide body of data now supports the idea that infectious prions consist principally or entirely of an abnormal iso form of PrP. Disease associated PrP, designated PrPSc, is derived from PrPc by a post-translational mechanism and neither amino acid sequencing nor systematic study of known covalent post-translational modifications have shown any consistent differences between PrPc and PrIJSt [5,20]. 

C. Much of collagen s strength arises from the special mechanism of its synthesis, post-translational modification, and assembly into collagen fibers (Figure 2-3). 

Other post-translational modifications of proteins (e.g., phosphorylation) are extremely important mechanisms of regulation of enzyme activity. Very tittle work has been done on the effects of such modifications on enzyme stabilization. 

Many proteins synthesized in a cell are modified. For example, carbohydrates are often attached to the proteins found in cell membrane. Some proteins become phosphorylated. Such modifications either activate or inactivate the function of the protein. Therefore, a foreign gene should be properly manipulated to obtain a correct post-translational modification. For example, if an attachment of a carbohydrate to a protein is desired, one may design the process so as to secrete the protein out of a cell membrane. During this procedure the protein can be properly modified. However, such modification mechanisms can be different in each living organism. Therefore, careful selection of a proper cell line is necessary. 

Fersht, A. (1985) Enzyme Structure and Mechanism, 2nd edition. W. H. Freeman, New York. Freeman, R. B., and Hawkins, H. C., Eds. (1980, 1985) The Enzymology of Post-translational Modifications of Proteins, Vols. 1 and 2. Academic Press, New York. 

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