'''Crystal structure of human gamma-tubulin bound to GTPgammaS'''
===Crystal structure of human gamma-tubulin bound to GTPgammaS===
==Overview==
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Microtubules are hollow polymers of alphabeta-tubulin that show GTP-dependent assembly dynamics and comprise a critical part of the eukaryotic cytoskeleton. Initiation of new microtubules in vivo requires gamma-tubulin, organized as an oligomer within the 2.2-MDa gamma-tubulin ring complex (gamma-TuRC) of higher eukaryotes. Structural insight is lacking regarding gamma-tubulin, its oligomerization and how it promotes microtubule assembly. Here we report the 2.7-A crystal structure of human gamma-tubulin bound to GTP-gammaS (a non-hydrolysable GTP analogue). We observe a 'curved' conformation for gamma-tubulin-GTPgammaS, similar to that seen for GDP-bound, unpolymerized alphabeta-tubulin. Tubulins are thought to represent a distinct class of GTP-binding proteins, and conformational switching in gamma-tubulin might differ from the nucleotide-dependent switching of signalling GTPases. A crystal packing interaction replicates the lateral contacts between alpha- and beta-tubulins in the microtubule, and this association probably forms the basis for gamma-tubulin oligomerization within the gamma-TuRC. Laterally associated gamma-tubulins in the gamma-TuRC might promote microtubule nucleation by providing a template that enhances the intrinsically weak lateral interaction between alphabeta-tubulin heterodimers. Because they are dimeric, alphabeta-tubulins cannot form microtubule-like lateral associations in the curved conformation. The lateral array of gamma-tubulins we observe in the crystal reveals a unique functional property of a monomeric tubulin.
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==About this Structure==
==About this Structure==
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[[Category: Stearns, T.]]
[[Category: Stearns, T.]]
[[Category: Structural protein]]
[[Category: Structural protein]]
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Revision as of 09:30, 28 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
1Z5V is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Insights into microtubule nucleation from the crystal structure of human gamma-tubulin., Aldaz H, Rice LM, Stearns T, Agard DA, Nature. 2005 May 26;435(7041):523-7. PMID:15917813
