Docked granules, the exocytic burst, and the need for ATP hydrolysis in endocrine cells

T. D. Parsons, J. R. Coorssen, H. Horstmann, W. Almers

Research output: Contribution to journalArticle

297 Scopus citations

Abstract

Ca2+-triggered exocytosis was studied in single rat melanotrophs and bovine chromaffin cells by capacitance measurements. Sustained exocytosis required MgATP, but even in the absence of MgATP, Ca2+ could trigger exocytosis of 2700 granules in a typical melanotroph and of 840 granules in a chromaffin cell. Granules undergoing ATP-independent exocytosis were similar in number to those appearing docked to the plasmalemma in quickly frozen unfixed sections (3300 in a melanotroph and 830 in a chromaffin cell). Most exocytosis required tens of second, but a small pool of granules was released in tens of milliseconds. Evidently, only a small subset of docked granules is rapidly releasable. We suggest that, temporally, the last ATP-dependent step in exocytosis is closely associated with docking and that docked granules reach fusion competence only after subsequent steps.

Original languageEnglish (US)
Pages (from-to)1085-1096
Number of pages12
JournalNeuron
Volume15
Issue number5
DOIs
StatePublished - Nov 1995

ASJC Scopus subject areas

  • Neuroscience(all)

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