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Mol Biol Cell. 2014 Oct 1;25(19):2984-92. doi: 10.1091/mbc.E13-09-0514. Epub 2014 Aug 7.

The Caenorhabditis elegans pericentriolar material components SPD-2 and SPD-5 are monomeric in the cytoplasm before incorporation into the PCM matrix.

Author information

1
Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
2
Department of Clinical Biochemistry, Copenhagen University Hospital Hvidovre, 2650 Hvidovre, Denmark Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark.
3
Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
4
Department of Cellular and Molecular Medicine, Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093.
5
Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark.
6
Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany hyman@mpi-cbg.de.

Abstract

Centrosomes are the main microtubule-organizing centers in animal cells. Centrosomes consist of a pair of centrioles surrounded by a matrix of pericentriolar material (PCM) that assembles from cytoplasmic components. In Caenorhabditis elegans embryos, interactions between the coiled-coil proteins SPD-5 and SPD-2 and the kinase PLK-1 are critical for PCM assembly. However, it is not known whether these interactions promote the formation of cytoplasmic complexes that are added to the PCM or whether the components interact only during incorporation into the PCM matrix. Here we address this problem by using a combination of live-cell fluorescence correlation spectroscopy, mass spectrometry, and hydrodynamic techniques to investigate the native state of PCM components in the cytoplasm. We show that SPD-2 is monomeric, and neither SPD-2 nor SPD-5 exists in complex with PLK-1. SPD-5 exists mostly as a monomer but also forms complexes with the PP2A-regulatory proteins RSA-1 and RSA-2, which are required for microtubule organization at centrosomes. These results suggest that the interactions between SPD-2, SPD-5, and PLK-1 do not result in formation of cytoplasmic complexes, but instead occur in the context of PCM assembly.

PMID:
25103243
PMCID:
PMC4230587
DOI:
10.1091/mbc.E13-09-0514
[Indexed for MEDLINE]
Free PMC Article

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