Polyglutamylation

Polyglutamylation is a form of reversible posttranslational modification of glutamate residues seen for example in alpha and beta tubulins, 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.[1] 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.[2]

External links

  • The role of tubulin polymodifications in microtubule functions

References

  1. ^ "Polyglutamylation: mechanism". Archived from the original on 2012-07-24. Retrieved 2010-04-12.
  2. ^ Boucher D, Larcher JC, Gros F, Denoulet P (October 1994). "Polyglutamylation of tubulin as a progressive regulator of in vitro interactions between the microtubule-associated protein Tau and tubulin". Biochemistry. 33 (41): 12471–7. doi:10.1021/bi00207a014. PMID 7522559.
  • v
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Protein primary structure and posttranslational modifications
General
  • Peptide bond
  • Protein biosynthesis
  • Proteolysis
  • Racemization
  • N–O acyl shift
N terminus
  • Acetylation
  • Carbamylation
  • Formylation
  • Glycation
  • Methylation
  • Myristoylation (Gly)
C terminusSingle specific AAs
Serine/Threonine
Tyrosine
Cysteine
Aspartate
Glutamate
Asparagine
Glutamine
Lysine
Arginine
Proline
Histidine
Tryptophan
Crosslinks between two AAs
CysteineCysteine
MethionineHydroxylysine
LysineTyrosine
  • Lysine tyrosylquinone (LTQ) formation
TryptophanTryptophan
Crosslinks between three AAs
SerineTyrosineGlycine
HistidineTyrosineGlycine
  • 4-(p-hydroxybenzylidene)-5-imidazolinone (HBI) formation (chromophore)
AlanineSerineGlycine
Crosslinks between four AAs
AllysineAllysineAllysineLysine