Phosphotransferases Associated with the Regulation of Kinesin Motor Activity*
- From the ‡Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710 and§Department of Pathology, University of Chicago, Chicago, Illinois 60637
Abstract
Kinesin, a plus-end-directed microtubule motor protein, functions in concert with accessory factors that have been shown to regulate enzyme activity and may also provide cargo specificity. This report identifies the 79-kDa kinesin-associated phosphoprotein as a phosphoisoform of kinesin light chain. Increased phosphorylation of this light chain isoform is sufficient to account for the increase in kinesin-mediated microtubule-gliding activity. Additionally, it was found that the degree of phosphorylation of this isoform is regulated by a 100-kDa kinase and 150-kDa type 1 phosphatase. Both the kinesin light chain kinase and phosphatase co-purify with the kinesin heavy chain, suggesting that kinesin exists in a large complex capable of self-regulation.
Footnotes
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↵* This work was supported by Grants from the National Institutes of Health and the American Cancer Society.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.
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↵¶ To whom correspondence should be addressed: Dept. of Cell Biology, Box 3709, Duke University Medical Center, Durham, NC 27710. Tel.: 919-684–8091; Fax: 919-684-8592; E-mail:m.sheetz{at}cellbio.duke.edu.
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↵1 The abbreviations used are: MT, microtubule; OA, okadaic acid; PPase, protein phosphatase; KAPP, kinesin-associated phosphoprotein; KHC, kinesin heavy chain; KLC, kinesin light chain; PMEE, 35mm 1.4 piperazinediethane sulfonic acid (PIPES), pH 7.4, 5 mm MgSO4, 5 mm, EGTA, 0.5 mm EDTA, 1 mm dithiothreitol and protease inhibitor cocktail; PAGE, polyacrylamide gel electrophoresis; I-2, inhibitor-2; SUK4, anti-kinesin heavy chain monoclonal antibody; CKLC.2.7F8, anti-kinesin light chain monoclonal antibody; CKLC.3.9C1, anti-kinesin light chain monoclonal antibody; PP2A, protein phosphatase type 2A; PP1, protein phosphatase type 1.
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↵2 J. M. McIlvain, Jr., unpublished results.
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- Received March 26, 1997.
- Revision received June 11, 1997.
