QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 16, Issue 10, 4827-4840, October 2005

This Article Full Text Full Text (PDF) All Versions of this Article: E05-04-0315v1 16/10/4827    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Roig, J. Articles by Avruch, J. Search for Related Content PubMed PubMed Citation Articles by Roig, J. Articles by Avruch, J.

Active Nercc1 Protein Kinase Concentrates at Centrosomes Early in Mitosis and Is Necessary for Proper Spindle Assembly

Joan Roig ^*, Aaron Groen , Jennifer Caldwell , and Joseph Avruch ^*

^* Department of Molecular Biology and Medical Services, Massachusetts General Hospital and Department of Medicine, Harvard Medical School, Boston, MA 02114; Department of Systems Biology, Harvard Medical School, Boston, MA 02115; and MDS Proteomics, Charlottesville, VA 22911

Submitted April 15, 2005; Revised July 21, 2005; Accepted July 22, 2005
Monitoring Editor: Yixian Zheng

The Nercc1 protein kinase autoactivates in vitro and is activated in vivo during mitosis. Autoactivation in vitro requires phosphorylation of the activation loop at threonine 210. Mitotic activation of Nercc1 in mammalian cells is accompanied by Thr210 phosphorylation and involves a small fraction of total Nercc1. Mammalian Nercc1 coimmunoprecipitates -tubulin and the activated Nercc1 polypeptides localize to the centrosomes and spindle poles during early mitosis, suggesting that active Nercc has important functions at the microtubular organizing center during cell division. To test this hypothesis, we characterized the Xenopus Nercc1 orthologue (XNercc). XNercc endogenous to meiotic egg extracts coprecipitates a multiprotein complex that contains -tubulin and several components of the -tubulin ring complex and localizes to the poles of spindles formed in vitro. Reciprocally, immunoprecipitates of the -tubulin ring complex polypeptide Xgrip109 contain XNercc. Immunodepletion of XNercc from egg extracts results in delayed spindle assembly, fewer bipolar spindles, and the appearance of aberrant microtubule structures, aberrations corrected by addition of purified recombinant XNercc. XNercc immunodepletion also slows aster assembly induced by Ran-GTP, producing Ran-asters of abnormal size and morphology. Thus, Nercc1 contributes to both the centrosomal and the chromatin/Ran pathways that collaborate in the organization of a bipolar spindle.

Abbreviations used: -TuRC, -tubulin ring complex; MS, mass spectrometry; CSF, cytostatic factor.

Address correspondence to: Joan Roig (roig{at}molbio.mgh.harvard.edu) or Joseph Avruch (avruch{at}helix.mgh.harvard.edu).

This article has been cited by other articles:

				P. Rellos, F. J. Ivins, J. E. Baxter, A. Pike, T. J. Nott, D.-M. Parkinson, S. Das, S. Howell, O. Fedorov, Q. Y. Shen, et al. Structure and Regulation of the Human Nek2 Centrosomal Kinase J. Biol. Chem., March 2, 2007; 282(9): 6833 - 6842. [Abstract] [Full Text] [PDF]

				L. M. Quarmby and M. R. Mahjoub Caught Nek-ing: cilia and centrioles J. Cell Sci., November 15, 2005; 118(22): 5161 - 5169. [Abstract] [Full Text] [PDF]