Research Output

Stability of the small γ-tubulin complex requires HCA66, a protein of the centrosome and the nucleolus.

  To investigate changes at the centrosome during the cell cycle,
we analyzed the composition of the pericentriolar material
from unsynchronized and S-phase-arrested cells by gel
electrophoresis and mass spectrometry. We identified HCA66,
a protein that localizes to the centrosome from S-phase to mitosis
and to the nucleolus throughout interphase. Silencing of HCA66
expression resulted in failure of centrosome duplication
and in the formation of monopolar spindles, reminiscent
of the phenotype observed after γ-tubulin silencing.
Immunofluorescence microscopy showed that proteins of the
γ-tubulin ring complex were absent from the centrosome in
these monopolar spindles. Immunoblotting revealed reduced
protein levels of all components of the γ-tubulin small complex
(γ-tubulin, GCP2, and GCP3) in HCA66-depleted cells. By
contrast, the levels of γ-tubulin ring complex proteins such as
GCP4 and GCP-WD/NEDD1 were unaffected. We propose that
HCA66 is a novel regulator of γ-tubulin function that plays a
role in stabilizing components of the γ-tubulin small complex,
which is in turn essential for assembling the larger γ-tubulin
ring complex.

  • Type:


  • Date:

    30 November 2008

  • Publication Status:


  • Publisher

    The Company of Biologists

  • DOI:


  • ISSN:


  • Library of Congress:

    QH301 Biology

  • Dewey Decimal Classification:

    572 Biochemistry


Fant, X., Gnadt, N., Haren, L. & Merdes, A. (2008). HCA66, a protein of the centrosome and the nucleolus. Journal of Cell Science. 122, 1134-1144. doi:10.1242/jcs.035238. ISSN 0021-9533



Centrosome; γ-Tubulin; Mitosis; Monopolar; Spindle;

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