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Posttranslational modification (PTM) is a step in protein biosynthesis. Proteins are created by ribosomes translating mRNA into polypeptide chains. These polypeptide chains undergo PTM, (such as folding, cutting and other processes), before becoming the mature protein product.


Posttranslational modification of insulin. At the top, the ribosome translates a mRNA sequence into a protein, insulin, and passes the protein through the endoplasmic reticulum, where it is cut, folded and held in shape by disulfide (-S-S-) bonds. Then the protein passes through the golgi apparatus, where it is packaged into a vesicle. In the vesicle, more parts are cut off, and it turns into mature insulin.

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

PTMs involving addition of functional groups Edit


PTMs involving addition by an enzyme in vivoEdit

PTMs involving addition of hydrophobic groups for membrane localizationEdit

PTMs involving addition of cofactors for enhanced enzymatic activityEdit

PTMs involving unique modifications of translation factorsEdit

PTMs involving addition of smaller chemical groupsEdit

PTMs involving non-enzymatic additions in vivoEdit

  • glycation, the addition of a sugar molecule to a protein without the controlling action of an enzyme.

PTMs involving non-enzymatic additions in vitroEdit

PTMs involving addition of other proteins or peptides Edit

PTMs involving changing the chemical nature of amino acids Edit

PTMs involving structural changes Edit

Post-translational modification statistics Edit

Recently, statistics of each post-translational modification experimentally and putatively detected have been compiled using proteome-wide information from the Swiss-Prot database.[13] These statistics can be found at

Case examples Edit

External linksEdit

References Edit

  1. Gramatikoff K. in Abgent Catalog (2004-5) p.263
  2. Whiteheart SW, Shenbagamurthi P, Chen L, et al. (1989). Murine elongation factor 1 alpha (EF-1 alpha) is posttranslationally modified by novel amide-linked ethanolamine-phosphoglycerol moieties. Addition of ethanolamine-phosphoglycerol to specific glutamic acid residues on EF-1 alpha.. J. Biol. Chem. 264 (24): 14334–41.
  3. 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.
  4. Yang XJ, Seto E (2008). Lysine acetylation: codified crosstalk with other posttranslational modifications. Mol Cell 31 (4): 449–61.
  5. 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.
  6. Glozak MA, Sengupta N, Zhang X, Seto E (2005). Acetylation and deacetylation of non-histone proteins. Gene 363: 15–23.
  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.
  8. Walker CS, Shetty RP, Clark K, et al. (2001). On a potential global role for vitamin K-dependent gamma-carboxylation in animal systems. Animals can experience subvaginalhemototitis as a result of this linkage. Evidence for a gamma-glutamyl carboxylase in Drosophila. J. Biol. Chem. 276 (11): 7769–74.
  9. 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.
  10. Van G. Wilson (Ed.) (2004). Sumoylation: Molecular Biology and Biochemistry. Horizon Bioscience. ISBN 0-9545232-8-8.
  11. Brennan DF, Barford D (2009). Eliminylation: a post-translational modification catalyzed by phosphothreonine lyases. Trends in Biochemical Sciences 34 (3): 108–114.
  12. Mydel P, et al. (2010). Carbamylation-dependent activation of T cells: a novel mechanism in the pathogenesis of autoimmune arthritis.. Journal of Immunology 184 (12): 6882–6890.
  13. Khoury, George A.; Baliban, Richard C.; and Christodoulos A. Floudas (2011). Proteome-wide post-translational modification statistics: frequency analysis and curation of the swiss-prot database. Scientific Reports 1 (90).

Protein primary structure and posttranslational modifications
General: Protein biosynthesis | Peptide bond | Proteolysis | Racemization | N-O acyl shift
N-terminus: Acetylation | Formylation | Myristoylation | Pyroglutamate | methylation | glycation | myristoylation (Gly) | carbamylation
C-terminus: Amidation | Glycosyl phosphatidylinositol (GPI) | O-methylation | glypiation | ubiquitination | sumoylation
Lysine: Methylation | Acetylation | Acylation | Hydroxylation | Ubiquitination | SUMOylation | Desmosine | deamination and oxidation to aldehyde| O-glycosylation | imine formation | glycation | carbamylation
Cysteine: Disulfide bond | Prenylation | Palmitoylation
Serine/Threonine: Phosphorylation | Glycosylation
Tyrosine: Phosphorylation | Sulfation | porphyrin ring linkage | flavin linkage | GFP prosthetic group (Thr-Tyr-Gly sequence) formation | Lysine tyrosine quinone (LTQ) formation | Topaquinone (TPQ) formation
Asparagine: Deamidation | Glycosylation
Aspartate: Succinimide formation
Glutamine: Transglutamination
Glutamate: Carboxylation | polyglutamylation | polyglycylation
Arginine: Citrullination | Methylation
Proline: Hydroxylation
←Amino acids Secondary structure→

Template:Posttranslational modification Template:Gene expression

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