The Heterotrimeric GTP-Binding Protein, GS, Modulates The Cl−Conductance of Rat Parotid Acinar Secretory Granules

Gsαhas been reported to be present in rat parotid acinar secretory granule membrane (SGM) fractions. In the present study, we evaluated epitope orientation of Gsαon the secretory granule (SG) and the ability of Gsto modulate the Cl−conductance of isolated granules by measuring granule lysis. Gsαwas...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 1997-09, Vol.238 (2), p.638-642
Main Authors: Watson, Eileen L., Izutsu, Kenneth T., Jacobson, Kerry L., Dijulio, Dennis H.
Format: Article
Language:English
Subjects:
Animals
Chlorides - metabolism
Cytoplasmic Granules - metabolism
Epitopes
GTP-Binding Protein alpha Subunits, Gs - metabolism
Parotid Gland - metabolism
Parotid Gland - ultrastructure
Rats
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Summary:Gsαhas been reported to be present in rat parotid acinar secretory granule membrane (SGM) fractions. In the present study, we evaluated epitope orientation of Gsαon the secretory granule (SG) and the ability of Gsto modulate the Cl−conductance of isolated granules by measuring granule lysis. Gsαwas found to be associated with the cytoplasmic face of the SGM. Aluminum fluroide (AlF4−, 20μM Al3+and 10 mM F−) significantly increased granule lysis and this effect was blocked by GDPβS. Cholera toxin (5μg/ml) mimicked the effects of AlF4−on granule lysis, whereas pertussis toxin (0.5μg/ml) was without effect. GTPγS, however, reduced granule lysis in a concentration-dependent manner. The orientation of Gsαon the SGM as well as the effects of AlF4−and cholera toxin on granule lysis lends support for a role of Gsin the exocytotic process.
ISSN:0006-291X
1090-2104
DOI:10.1006/bbrc.1997.7354