Post-translational modification: Difference between revisions
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''Post-translational modification'' ('''PTM''') refers to chemical modification of [[amino acids]] after they have been incorporated into protein chains in sequences specified by the genome. PTM affect the functions of proteins. More than 200 kinds of PTM are known, affecting 15 of the 20 standard [[amino acids]]<ref name="kesselbental">Kessel, Amit, and Ben-Tal, Nir. Introduction to proteins: structure, function, and motion. CRC Press, 2011.</ref><ref>PMID: 16267872</ref>. | ''Post-translational modification'' ('''PTM''') refers to chemical modification of [[amino acids]] after they have been incorporated into protein chains in sequences specified by the genome. Proteolysis of protein chains is another form of PTM. PTM affect the functions of proteins. More than 200 kinds of PTM are known, affecting 15 of the 20 standard [[amino acids]]<ref name="kesselbental">Kessel, Amit, and Ben-Tal, Nir. Introduction to proteins: structure, function, and motion. CRC Press, 2011.</ref><ref>PMID: 16267872</ref>. | ||
==Chemical Nature== | ==Chemical Nature== | ||
PTM include<ref name="kesselbental" /> | PTM include<ref name="kesselbental" /> | ||
* | *Phosphorylation, notably of tyrosine, serine, or threonine, effected by'' protein kinases''. | ||
* | **Dephosphorylation is accomplished by ''protein phosphatases''. | ||
*acylation | *Glycosylation, notably of asparagine (''N-linked glycosylation''), serine, or threonine. | ||
* | *Acylation: attachment of acyl carboxylic acids, most commonly acetic (C<sub>2</sub>), myristic (C<sub>14</sub>), and palmitic (C<sub>16</sub>) acids. | ||
* | **[[Ubiquitin]] is attached to proteins by acylation, using its carboxy-terminal glycine to form an isopeptide bond with a lysine in the target protein. | ||
**De-acylation is accomplished by ''de-acylases''. | |||
*Alkylation, notably methylation, S-prenylation, and adenylation. | |||
*Oxidation, notably creating hydroxylated proline, lysine, asparagine, and glutamic acid, as well as sulfation or [[nitrotyrosine|nitrosylation]] of tyrosine. | |||
*C-terminal amidation, neutralizing the charge. | |||
*ADP ribosylation, a common mechanism used by bacterial toxins. | |||
*Disulfide bond formation. | |||
*Proteolysis. | |||
==Consequences for Function== | |||
PTM induce conformational changes in proteins, and affect oligomerization and [[ligand]] binding. PTM may affect catalysis by direct modification of catalytic residues, modification of nearby residues, or effects on regulation. | |||
==Consequences for Proteome== | ==Consequences for Proteome== | ||
