Polyglutamylation is a form of reversible posttranslational modification of

glutamate Glutamic acid (symbol Glu or E; known as glutamate in its anionic form) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a Essential amino acid, non-essential nutrient for humans, meaning that ...

residues seen for example in alpha and beta

tubulins Tubulin in molecular biology can refer either to the tubulin protein superfamily of globular proteins, or one of the member proteins of that superfamily. α- and β-tubulins polymerize into microtubules, a major component of the eukaryotic cytosk ...

, nucleosome assembly proteins NAP1 and NAP2. The γ-carboxy group of glutamate may form peptide-like bond with the

amino group In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

of a free glutamate whose α-

carboxy group In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl group (e.g. ...

can now be extended into a polyglutamate chain. The glutamylation is done by the enzyme glutamylase and removed by deglutamylase. Polyglutamylation of chain length of up to six occurs in certain glutamate residues near the C terminus of most major forms of tubulins. These residues, though themselves not involved in direct binding, cause conformational shifts that regulate binding of microtubule associated proteins (MAP and Tau) and motors.

External links

The role of tubulin polymodifications in microtubule functions

References

{{Protein primary structure Post-translational modification Protein structure