This Article Full Text Full Text (PDF) Other Versions of this Article: MCB.02235-06v1 27/12/4431    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 Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cline, E. G. Articles by Nelson, W. J. Search for Related Content PubMed PubMed Citation Articles by Cline, E. G. Articles by Nelson, W. J.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, June 2007, p. 4431-4443, Vol. 27, No. 12
0270-7306/07/$08.00+0     doi:10.1128/MCB.02235-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Characterization of Mammalian Par 6 as a Dual-Location Protein

Departments of Biological Sciences and Molecular and Cellular Physiology, Stanford University, Stanford, California

Received 28 November 2006/ Returned for modification 30 January 2007/ Accepted 27 March 2007

Par 6 acts as a scaffold protein to facilitate atypical protein kinase C-mediated phosphorylation of cytoplasmic protein complexes, leading to epithelial and neuronal cell polarization. In addition to its location in the cytoplasm, Par 6 is localized to the nucleus. However, its organization and potential functions in the nucleus have not been examined. Using an affinity-purified Par 6 antibody and a chimera of Par 6 and green fluorescent protein, we show that Par 6 localizes precisely to nuclear speckles, but not to other nuclear structures, and displays characteristics of speckle proteins. We show that Par 6 colocalizes in the nucleus with Tax, a transcriptional activator of the human T-cell leukemia virus type 1 long terminal repeat, but multiple lines of evidence show that Par 6 is not directly involved in known functions of speckle proteins, including general transcription, splicing, or mRNA transport. Significantly, however, the structure of nuclear speckles is lost when Par 6 levels are reduced by Par 6-specific small interfering RNA. Therefore, we hypothesize that Par 6 in the nucleus acts as a scaffolding protein in nuclear speckle complexes, similar to its role in the cytoplasm.

Published ahead of print on 9 April 2007.

This article has been cited by other articles:

• Costa, M. R., Wen, G., Lepier, A., Schroeder, T., Gotz, M. (2008). Par-complex proteins promote proliferative progenitor divisions in the developing mouse cerebral cortex. Development 135: 11-22 [Abstract] [Full Text]