Specific Isoforms of Actin-binding Proteins on Distinct Populations of Golgi-derived Vesicles*
- From the ‡Centre for Molecular and Cellular Biology, University of Queensland, Brisbane, Queensland 4072 and the§Oncology Research Unit, The New Children’s Hospital, Westmead, and Department of Paediatrics and Child Health, University of Sydney, Sydney, New South Wales 2145, Australia
Abstract
Golgi membranes and Golgi-derived vesicles are associated with multiple cytoskeletal proteins and motors, the diversity and distribution of which have not yet been defined. Carrier vesicles were separated from Golgi membranes, using an in vitro budding assay, and different populations of vesicles were separated using sucrose density gradients. Three main populations of vesicles labeled with β-COP, γ-adaptin, or p200/myosin II were separated and analyzed for the presence of actin/actin-binding proteins. β-Actin was bound to Golgi cisternae and to all populations of newly budded vesicles. Centractin was selectively associated with vesicles co-distributing with β-COP-vesicles, while p200/myosin II (non-muscle myosin IIA) and non-muscle myosin IIB were found on different vesicle populations. Isoforms of the Tm5 tropomyosins were found on selected Golgi-derived vesicles, while other Tm isoforms did not colocalize with Tm5 indicating the association of specialized actin filaments with Golgi-derived vesicles. Golgi-derived vesicles were shown to bind to F-actin polymerized from cytosol with Jasplakinolide. Thus, newly budded, coated vesicles derived from Golgi membranes can bind to actin and are customized for differential interactions with microfilaments by the presence of selective arrays of actin-binding proteins.
Footnotes
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↵* This work was supported in part by National Health and Medical Research Council (NHMRC) grants (to J. L. S., P. G., and R. W.).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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↵¶ Senior Research Fellow of the NHMRC.
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↵‖ Senior Medical Research Fellow of the Wellcome Trust. To whom correspondence should be addressed. Tel.: 61-7-3365-4985; Fax: 61-7-3365-4388; E-mail: j.stow{at}cmcb.uq.edu.au.
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↵2 K. Heimann and J. L. Stow, unpublished observations.
- Abbreviations:
- TGN
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trans-Golgi network
- mAb
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monoclonal antibody
- GTPγS
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guanosine 5′-O-(3-thiotriphosphate)
- PAGE
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polyacrylamide gel electrophoresis
- JAS
-
Jasplakinolide
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- Received December 17, 1998.
- Revision received February 2, 1999.
- The American Society for Biochemistry and Molecular Biology, Inc.
