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''. | **Dephosphorylation is accomplished by ''protein phosphatases''. | ||
*Glycosylation, notably of asparagine (''N-linked glycosylation''), serine, or threonine. | *Glycosylation, notably of asparagine (''N-linked glycosylation''), serine, or threonine. | ||
| Line 11: | Line 11: | ||
*Alkylation, notably methylation, S-prenylation, and adenylation. | *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. | *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. | 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. | ||
Latest revision as of 22:30, 15 September 2011
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[1][2].
Chemical NatureChemical Nature
PTM include[1]
- Phosphorylation, notably of tyrosine, serine, or threonine, effected by protein kinases.
- Dephosphorylation is accomplished by protein phosphatases.
- Glycosylation, notably of asparagine (N-linked glycosylation), serine, or threonine.
- Acylation: attachment of acyl carboxylic acids, most commonly acetic (C2), myristic (C14), and palmitic (C16) 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 nitrosylation of tyrosine.
- C-terminal amidation, neutralizing the charge.
- ADP ribosylation, a common mechanism used by bacterial toxins.
- Disulfide bond formation.
- Proteolysis.
Consequences for FunctionConsequences 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 ProteomeConsequences for Proteome
About 5% of the genome of eukaryotes is devoted to enzymes that carry out PTM[1]. PTM may increase the number of unique proteins in an organism by more than an order of magnitude.
LIterature CitedLIterature Cited
- ↑ 1.0 1.1 1.2 Kessel, Amit, and Ben-Tal, Nir. Introduction to proteins: structure, function, and motion. CRC Press, 2011.
- ↑ Walsh CT, Garneau-Tsodikova S, Gatto GJ Jr. Protein posttranslational modifications: the chemistry of proteome diversifications. Angew Chem Int Ed Engl. 2005 Dec 1;44(45):7342-72. PMID:16267872 doi:10.1002/anie.200501023