Disturbance of the secretory pathway inMicrasterias denticulata by tunicamycin and cyclopiazonic acid |
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Authors: | Margit Höftberger T Url Ursula Meindl |
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Institution: | (1) Institut für Pflanzenphysiologie, Universität Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria |
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Abstract: | Summary Both tunicamycin, an inhibitor of N-linked glycosylation of proteins, and cyclopiazonic acid, which inhibits the Ca2+-dependent ATPase in the ER, influence the secretory pathway at the ER level and lead to a cessation of cell growth inMicrasterias. Electron microscopical investigations reveal that the mode of action of the two inhibitors differs. While tunicamycin treatment results in a disintegration of the Golgi bodies into small vesicles, cyclopiazonic acid prevents products being supplied from the ER, resulting in the dilatation of ER cisternae and a reduction in the number of Golgi cisternae, combined with a loss of dictyosomal activity. The disturbed cell wall formation under tunicamycin indicates that N-linked glycosylation of proteins is required for normal cell growth inMicrasterias. Moreover, our studies reveal that changes in cytoplasmic free calcium concentration, as a consequence of ATPase inhibition in the ER by cyclopiazonic acid, may inhibit wall material secretion by interrupting the normal ER-dictyosome association.Abbreviations CPA
cyclopiazonic acid
- ER
endoplasmic reticulum
- TM
tunicamycin |
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Keywords: | Cyclopiazonic acid Golgi apparatus Micrasterias Secretory pathway Tunicamycin Ultrastructure |
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