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Originally published In Press as doi:10.1074/jbc.M600522200 on July 11, 2006
J. Biol. Chem., Vol. 281, Issue 37, 27216-27228, September 15, 2006
Mapping the GRIF-1 Binding Domain of the Kinesin, KIF5C, Substantiates a Role for GRIF-1 as an Adaptor Protein in the Anterograde Trafficking of Cargoes*
Miriam J. Smith12,
Karine Pozo1,
Kieran Brickley, and
F. Anne Stephenson3
From the
Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, United Kingdom
-Aminobutyric acid, type A (GABAA) receptor interacting factor-1 (GRIF-1) and N-acetylglucosamine transferase interacting protein (OIP) 106 are both members of a newly identified coiled-coil family of proteins. They are kinesin-associated proteins proposed to function as adaptors in the anterograde trafficking of organelles to synapses. Here we have studied in more detail the interaction between the prototypic kinesin heavy chain, KIF5C, kinesin light chain, and GRIF-1. The GRIF-1 binding site of KIF5C was mapped using truncation constructs in yeast two-hybrid interaction assays, co-immunoprecipitations, and co-localization studies following expression in mammalian cells. Using these approaches, it was shown that GRIF-1 and the KIF5C binding domain of GRIF-1, GRIF-1-(124-283), associated with the KIF5C non-motor domain. Refined studies using yeast two-hybrid interactions and co-immunoprecipitations showed that GRIF-1 and GRIF-1-(124-283) associated with the cargo binding region within the KIF5C non-motor domain. Substantiation that the GRIF-1-KIF5C interaction was direct was shown by fluorescence resonance energy transfer analyses using fluorescently tagged GRIF-1 and KIF5C constructs. A significant fluorescence resonance energy transfer value was found between the C-terminal EYFP-tagged KIF5C and ECFP-GRIF-1, the C-terminal EYFP-tagged KIF5C non-motor domain and ECFP-GRIF-1, but not between the N-terminal EYFP-tagged KIF5C nor the EYFP-KIF5C motor domain and ECFP-GRIF-1, thus confirming direct association between the two proteins at the KIF5C C-terminal and GRIF-1 N-terminal regions. Co-immunoprecipitation and confocal imaging strategies further showed that GRIF-1 can bind to the tetrameric kinesin light-chain/kinesin heavy-chain complex. These findings support a role for GRIF-1 as a kinesin adaptor molecule requisite for the anterograde delivery of defined cargoes such as mitochondria and/or vesicles incorporating 2 subunit-containing GABAA receptors, in the brain.
Received for publication, January 18, 2006
, and in revised form, July 10, 2006.
* This work was funded by the Biotechnology and Biological Sciences Research Council, United Kingdom. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The on-line version of this article (available at http://www.jbc.org) contains supplemental Table S1 and Figs. S1 and S2.
1 Both authors contributed equally to this work.
2 Current address: Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
3 To whom correspondence should be addressed: Tel.: 44-207-753-5877; Fax: 44-207-753-5964; E-mail: anne.stephenson{at}pharmacy.ac.uk.

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Copyright © 2006 by the American Society for Biochemistry and Molecular Biology.
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