The Forkhead-associated Domain of Ki-67 Antigen Interacts with the Novel Kinesin-like Protein Hklp2*
- From the ‡Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan and the ¶Institute for Molecular and Cellular Biology, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan
Abstract
The Ki-67 antigen (pKi-67) is widely used as a cell proliferation marker protein. Its actual role in the cell cycle progression, however, is presently unclear. Using a two-hybrid screening in yeast, a novel protein, termed Hklp2 (humankinesin-like protein2), was identified and shown to interact with the forkhead-associated (FHA) domain of pKi-67. Hklp2 has 1388 amino acids and shows a striking similarity (a 53% identity in amino acids) to Xklp2, a plus-end directed kinesin-like motor found inXenopus. The interaction domain of Hklp2 was mapped to the portion that comprised residues 1017–1237 and that was phosphorylatedin vitro by incubating with mitotic but not interphasic HeLa cell extracts. That the interaction was striking in the mitotic extract was also verified. In addition, immunofluorescence using specific antibodies revealed an association between pKi-67 and Hklp2 at the periphery of mitotic chromosomes, largely in close proximity to the centromeres. These findings suggest that pKi-67 is involved in the progression of mitosis via its interaction with Hklp2.
Footnotes
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↵* This work was supported by Grant-in-Aid for Scientific Research on Priority Areas (B) 11237202 and Grant-in-Aid for COE Research 07CE2006 from the Japanese Ministry of Education, Science, Sports and Culture and by funds from the Mitsubishi Foundation and the Human Frontiers Science Program.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) .
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↵§ These authors contributed equally to this work.
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↵‖ To whom correspondence should be addressed. Tel.: 81-6-6879-3210; Fax: 81-6-6879-3219; E-mail: yyoneda@anat3.med.osaka-u.ac.jp.
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Published, JBC Papers in Press, June 30, 2000, DOI 10.1074/jbc.M003879200
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↵3 M. Takagi and Y. Yoneda, unpublished observation.
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↵2 M. Takagi, M. Sueishi, T. Saiwaki, and Y. Yoneda, manuscript in preparation.
- Abbreviations:
- FHA
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forkhead-associated
- GST
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glutathioneS-transferase
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- Received May 8, 2000.
- Revision received June 29, 2000.
- The American Society for Biochemistry and Molecular Biology, Inc.
