Localization of Tctex-1, a Cytoplasmic Dynein Light Chain, to the Golgi Apparatus and Evidence for Dynein Complex Heterogeneity*
- From the Departments of ‡Cell Biology and Anatomy and§Ophthalmology, Margaret M. Dyson Vision Research Institute, Cornell University Medical College, New York, New York 10021
Abstract
To date, much attention has been focused on the heavy and intermediate chains of the multisubunit cytoplasmic dynein complex; however, little is known about the localization or function of dynein light chains. In this study, we find that Tctex-1, a light chain of cytoplasmic dynein, localizes predominantly to the Golgi apparatus in interphase fibroblasts. Immunofluorescent staining reveals striking juxtanuclear staining characteristic of the Golgi apparatus as well as nuclear envelope and punctate cytoplasmic staining that often decorates microtubules. Tctex-1 colocalization with Golgi compartment markers, its distribution upon treatment with various pharmacological agents, and the cofractionation of Tctex-1-associated membranes with Golgi membranes are all consistent with a Golgi localization. The distribution of Tctex-1 in interphase cells only partially overlaps with the dynein intermediate chain and p150Glued upon immunofluorescence, but most of Tctex-1 is redistributed onto mitotic spindles along with other dynein/dynactin subunits. Using sequential immunoprecipitations, we demonstrate that there is a subset of Tctex-1 not associated with the intermediate chain at steady state; the converse also appears to be true. Distinct populations of dynein complexes are likely to exist, and such diversity may occur in part at the level of their light chain compositions.
Footnotes
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↵* This work was supported by National Institutes of Health Grant EY11307, the Foundation Fighting Blindness, and Research Preventing Blindness (to C.-H. S.); the Emil Holland Fund (to A. W. T.); and National Institutes of Health Tri-institutional Training Program in Vision Grant EY07138 (to J.-Z. C.).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 reported in this paper has been submitted to the GenBankTM/EMBL/DDBJ Data Bank with accession numberAF067370.
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↵¶ To whom correspondence should be addressed: Margaret M. Dyson Vision Research Inst., Cornell University Medical College, 1300 York Ave., New York, NY 10021. Tel.: 212-746-2291; Fax: 212-746-6670; E-mail: chsung{at}mail.med.cornell.edu.
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↵1 The abbreviations used are: DHCs, dynein heavy chains; DICs, dynein intermediate chains; DLCs, dynein light chains; NRK, normal rat kidney; TGN, trans-Golgi network; mAb, monoclonal antibody; FITC, fluorescein isothiocyanate; MDCK, Madin-Darby canine kidney; GST, glutathione S-transferase; MBP, maltose-binding protein; PBS, phosphate-buffered saline; PIPES, 1,4-piperazinediethanesulfonic acid; PFA, paraformaldehyde; BFA, brefeldin A; ER, endoplasmic reticulum.
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↵2 J.-Z. Chuang, A. W. Tai, and C.-H. Sung, manuscript in preparation.
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↵3 A. W. Tai, J.-Z. Chuang, and C.-H. Sung, unpublished observations.
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- Received December 3, 1997.
- Revision received April 27, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
