Polyglutamylation is a form of reversible posttranslational modification of
glutamate
Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can synt ...
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 of a free glutamate whose α-
carboxy group 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