Identification of a human centrosomal calmodulin-binding protein that shares homology with pericentrin

Identification of a human centrosomal calmodulin-binding protein that shares homology with pericentrin

^*Program in Molecular and Cellular Biology, ^†Department of Pathology, and ^‡Department of Biochemistry, University of Washington, Seattle, WA 98195

Communicated by J. Richard McIntosh, University of Colorado, Boulder, CO (received for review October 6, 1999)

Abstract

Eukaryotic chromosome segregation depends on the mitotic spindle apparatus, a bipolar array of microtubules nucleated from centrosomes. Centrosomal microtubule nucleation requires attachment of γ-tubulin ring complexes to a salt-insoluble centrosomal core, but the factor(s) underlying this attachment remains unknown. In budding yeast, this attachment is provided by the coiled-coil protein Spc110p, which links the yeast γ-tubulin complex to the core of the yeast centrosome. Here, we show that the large coiled-coil protein kendrin is a human orthologue of Spc110p. We identified kendrin by its C-terminal calmodulin-binding site, which shares homology with the Spc110p calmodulin-binding site. Kendrin localizes specifically to centrosomes throughout the cell cycle. N-terminal regions of kendrin share significant sequence homology with pericentrin, a previously identified murine centrosome component known to interact with γ-tubulin. In mitotic human breast carcinoma cells containing abundant centrosome-like structures, kendrin is found only at centrosomes associated with spindle microtubules.

Footnotes

↵ § To whom reprint requests should be addressed. E-mail: tdavis{at}u.washington.edu.
↵ ¶ Accession numbers: Murine EST clones homologous to the C-terminal calmodulin-binding domain of three Spc110p-related fungal proteins, AA600395 and AA000932; human EST clone, AA333809; kendrin cDNA, U52962; PCNT, NM_006031; representative human EST clone homologous to the 3′ untranslated region of murine pericentrin but not homologous to any sequenced regions of human chromosome 21 (as of 1/25/2000), AI970199; human chromosome 21 contigs containing the kendrin genomic locus, NT_002306 and NT_002102.
Abbreviations:

SPB,

spindle pole body;

γ-TURC,

γ-tubulin ring complex;

GST,

glutathione S-transferase;

EST,

expressed sequence tag