Posttranslational modification: Wikis

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From Wikipedia, the free encyclopedia

Posttranslational modification (PTM) is the chemical modification of a protein after its translation. It is one of the later steps in protein biosynthesis for many proteins.

The bottom of this diagram shows the modification of primary structure of insulin, as described.

A protein (also called a polypeptide) is a chain of amino acids. During protein synthesis, 20 different amino acids can be incorporated in proteins. After translation, the posttranslational modification of amino acids extends the range of functions of the protein by attaching to it other biochemical functional groups such as acetate, phosphate, various lipids and carbohydrates, by changing the chemical nature of an amino acid (e.g. citrullination) or by making structural changes, like the formation of disulfide bridges.

Also, enzymes may remove amino acids from the amino end of the protein, or cut the peptide chain in the middle. For instance, the peptide hormone insulin is cut twice after disulfide bonds are formed, and a propeptide is removed from the middle of the chain; the resulting protein consists of two polypeptide chains connected by disulfide bonds. Also, most nascent polypeptides start with the amino acid methionine because the "start" codon on mRNA also codes for this amino acid. This amino acid is usually taken off during post-translational modification.

Other modifications, like phosphorylation, are part of common mechanisms for controlling the behavior of a protein, for instance activating or inactivating an enzyme.

Post-translational modification of proteins are detected by mass spectrometry or Eastern blotting.

Contents

PTMs involving addition of functional groups

The genetic code diagram[1] showing the amino acid residues as target of modification.

PTMs involving addition include:

(also see histone acetylation)[4][5]

PTMs involving addition of other proteins or peptides

PTMs involving changing the chemical nature of amino acids

PTMs involving structural changes

Case examples

External links

References

  1. ^ Gramatikoff K. in Abgent Catalog (2004-5) p.263
  2. ^ Polevoda B, Sherman F (2003). "N-terminal acetyltransferases and sequence requirements for N-terminal acetylation of eukaryotic proteins". J Mol Biol 325 (4): 595–622. doi:10.1016/S0022-2836(02)01269-X. PMID 12507466.  
  3. ^ Yang XJ, Seto E (2008). "Lysine acetylation: codified crosstalk with other posttranslational modifications". Mol Cell 31: 449–61. doi:10.1016/j.molcel.2008.07.002. PMID 18722172.  
  4. ^ Bártová E, Krejcí J, Harnicarová A, Galiová G, Kozubek S (2008). "Histone modifications and nuclear architecture: a review". J Histochem Cytochem 56 (8): 711–21. doi:10.1369/jhc.2008.951251. PMID 18474937.  
  5. ^ Glozak MA, Sengupta N, Zhang X, Seto E (2005). "Acetylation and deacetylation of non-histone proteins". Gene 363: 15–23. doi:10.1016/j.gene.2005.09.010. PMID 16289629.  
  6. ^ Walker CS, Shetty RP, Clark K, et al. (2001). "On a potential global role for vitamin K-dependent gamma-carboxylation in animal systems. Evidence for a gamma-glutamyl carboxylase in Drosophila". J. Biol. Chem. 276 (11): 7769–74. doi:10.1074/jbc.M009576200. PMID 11110799.  
  7. ^ Eddé B, Rossier J, Le Caer JP, Desbruyères E, Gros F, Denoulet P (1990). "Posttranslational glutamylation of alpha-tubulin". Science 247 (4938): 83–5. doi:10.1126/science.1967194. PMID 1967194.  
  8. ^ Malakhova, Oxana A.; Yan, Ming; Malakhov, Michael P.; Yuan, Youzhong; Ritchie, Kenneth J.; Kim, Keun Il; Peterson, Luke F.; Shuai, Ke; and Dong-Er Zhang (2003). "Protein ISGylation modulates the JAK-STAT signaling pathway". Genes & Development 17 (4): 455–60. doi:10.1101/gad.1056303. PMID 12600939. http://www.genesdev.org/cgi/content/full/17/4/455.  
  9. ^ Van G. Wilson (Ed.) (2004). Sumoylation: Molecular Biology and Biochemistry. Horizon Bioscience. ISBN 0-9545232-8-8.
  10. ^ Brennan DF, Barford D (2009). "Eliminylation: a post-translational modification catalyzed by phosphothreonine lyases". Trends in Biochemical Sciences 34 (3): 108–114. doi:10.1016/j.tibs.2008.11.005. PMID 19233656.  
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