Conserved Site

Tubulin, conserved site (IPR017975)

Short name: Tubulin_CS


Microtubules are polymers of tubulin, a dimer of two 55kDa subunits, designated alpha and beta [PMID: 3896122, PMID: 2194680]. Within the microtubule lattice, alpha-beta heterodimers associate in a head-to-tail fashion, giving rise to microtubule polarity. Fluorescent labelling studies have suggested that tubulin is oriented in microtubules with beta-tubulin toward the plus end [PMID: 8102497].

For maximal rate and extent of polymerisation into microtubules, tubulin requires GTP. Two molecules of GTP are bound at different sites, termed N and E. At the E (Exchangeable) site, GTP is hydrolysed during incorporation into the microtubule. Close to the E site is an invariant region rich in glycine residues, which is found in both chains and is thought to control access of the nucleotide to its binding site [PMID: 3680207].

Most species, excepting simple eukaryotes, express a variety of closely- related alpha- and beta-isotypes. A third family member, gamma tubulin, has also been identified in a number of species. Gamma tubulin is found at microtubule-organising centres, such as the spindle poles or the centrosome, suggesting that it is involved in minus-end nucleation of microtubule assembly [PMID: 8274140].

This entry represents the glycine-rich conserved site near the E (Exchangeable) site that controls the access of the nucleotide to its binding site.

GO terms

Biological Process

GO:0007017 microtubule-based process

Molecular Function

GO:0005525 GTP binding

Cellular Component

GO:0005874 microtubule

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns