1. Academic Validation
  2. GCP5 and GCP6: two new members of the human gamma-tubulin complex

GCP5 and GCP6: two new members of the human gamma-tubulin complex

  • Mol Biol Cell. 2001 Nov;12(11):3340-52. doi: 10.1091/mbc.12.11.3340.
S M Murphy 1 A M Preble U K Patel K L O'Connell D P Dias M Moritz D Agard J T Stults T Stearns
Affiliations

Affiliation

  • 1 Department of Biological Sciences, Stanford University, Stanford, California 94305-5020, USA.
Abstract

The gamma-tubulin complex is a large multiprotein complex that is required for microtubule nucleation at the centrosome. Here we report the purification and characterization of the human gamma-tubulin complex and the identification of its subunits. The human gamma-tubulin complex is a ring of ~25 nm, has a subunit structure similar to that reported for gamma-tubulin complexes from Other species, and is able to nucleate microtubule polymerization in vitro. Mass spectrometry analysis of the human gamma-tubulin complex components confirmed the presence of four previously identified components (gamma-tubulin and gamma-tubulin complex proteins [GCPs] 2, 3, and 4) and led to the identification of two new components, GCP5 and GCP6. Sequence analysis revealed that the GCPs share five regions of sequence similarity and define a novel protein superfamily that is conserved in metazoans. GCP5 and GCP6, like Other components of the gamma-tubulin complex, localize to the centrosome and associate with microtubules, suggesting that the entire gamma-tubulin complex takes part in both of these interactions. Stoichiometry experiments revealed that there is a single copy of GCP5 and multiple copies of gamma-tubulin, GCP2, GCP3, and GCP4 within the gamma-tubulin complex. Thus, the gamma-tubulin complex is conserved in structure and function, suggesting that the mechanism of microtubule nucleation is conserved.

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