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Cdk1 phosphorylation sites on Cdc27 are required for correct chromosomal localisation and APC/C function in syncytial Drosophila embryos

Lookup NU author(s): Dr Jun-yong Huang, Dr Gary Morley, Emeritus Professor Michael Whitaker

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Abstract

Anaphase-promoting complex or cyclosome (APC/C) controls the metaphase-to-anaphase transition and mitosis exit by triggering the degradation of key cell cycle regulators such as securin and B-type cyclins. However, little is known about the functions of individual APC/ C subunits and how they might regulate APC/C activity in space and time. Here, we report that two potential Cdk1 kinase phosphorylation sites are required for the chromosomal localisation of GFP::Cdc27 during mitosis. Either or both of the highly conserved proline residues in the Cdk1 phosphorylation consensus sequence motifs were mutated to alanine (Cdc27 P304A or P456A). The singly mutated fusion proteins, GFP::Cdc2lP304A and GFP::Cdc27P456A can still localise to mitotic chromosomes in a manner identical to wild-type GFP::Cdc27 and are functional in that they can rescue the phenotype of the cdc27L7123 mutant in vivo. However, when both of the Cdk1 phosphorylation sequence motifs re mutated, the resulting GFP::Cdc21P3O4A,6P456A construct was not localised to the chromosomes during mitosis and was no longer functional, as it failed to rescue mutant phenotypes of the cdc27L7123 gene. High levels of cyclin B and cyclin A were detected in mutant third instar larvae brain samples compared with its wild-type control. Those results show for the first time that the two potential Cdk1 phosphorylation sites on Drosophila Cdc27 are required Ibr its chromosomal localisation during mitosis and imply that these localisations specific to Cdc27 are crucial for APC/C functions.


Publication metadata

Author(s): Huang J-Y, Morley G, Li D, Whitaker M

Publication type: Article

Publication status: Published

Journal: Journal of Cell Science

Year: 2007

Volume: 120

Issue: 12

Pages: 1990-1997

Print publication date: 15/06/2007

ISSN (print): 0021-9533

ISSN (electronic): 1477-9137

Publisher: The Company of Biologists Ltd.

URL: http://dx.doi.org/10.1242/jcs.006833

DOI: 10.1242/jcs.006833

PubMed id: 17519285


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