Cysteine String Proteins Are Associated with Chromaffin Granules*
- From the Physiological Laboratory and the
- § Veterinary Preclinical Sciences Department, University of Liverpool, Liverpool L69 3BX, United Kingdom
- ¶ To whom correspondence should be addressed: Physiological Lab., University of Liverpool, Crown Street, Liverpool L69 3BX, UK. Tel.: 44-151-794-5305; Fax: 44-151-794-5337; E-mail: burgoyne{at}liverpool.ac.uk
Abstract
In this work, we have examined the subcellular distribution of cysteine string proteins (Csps) in bovine adrenal medullary chromaffin cells. Csps did not leak from digitonin-permeabilized chromaffin cells, suggesting that there is no cytosolic pool of the protein in these cells. Subcellular fractionation studies confirmed that there was essentially no Csp immunoreactivity in the cytosolic fraction. However, immunoreactivity was detected in the membrane fractions of these cells. Csp immunoreactivity codistributed with dopamine β-hydroxylase, a granule marker protein, in sucrose gradient-separated granule fractions. Immunofluorescence studies showed that all chromaffin cells in culture were stained with a punctate appearance consistent with a granular localization. These results were confirmed by immunogold labeling, which demonstrated specific labeling of chromaffin granule membranes. In addition to its presence on synaptic vesicles, cysteine string protein is therefore a bona fide chromaffin granule membrane protein.
Footnotes
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↵‡ Supported by a Wellcome Trust prize studentship.
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↵* This work was supported in part by a grant from the Wellcome Trust. 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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↵1 The abbreviations used are:
- Csps
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cysteine string proteins
- PBS
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phosphate-buffered saline.
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- Received April 18, 1996.
- Revision received May 20, 1996.
- © 1996 by The American Society for Biochemistry and Molecular Biology, Inc.
