Ca(2)+-stimulated exocytosis in maize coleoptile cells

J U Sutter, U Homann, G Thiel

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Changes in membrane capacitance (C(m)) after photolysis of the caged Ca(2)+ compound dimethoxynitrophenamine were studied in protoplasts from maize coleoptiles. Changes in C(m) values resulting from increased concentrations of free Ca(2)+ in the cytoplasm ([Ca(2)+](cyt)) were interpreted as representing changes in [Ca(2)+](cyt)-sensitive exocytosis and endocytosis. A continuous increase in [Ca(2)+](cyt) resulted in a sigmoidal increase in C(m) values with a half-maximal concentration at approximately 1 microM. The steep increase in C(m) values was followed by a variable slow phase in changing C(m) values. When [Ca(2)+](cyt) increased at a rate of 0.6 micromol L(-)(1) sec(-)(1), the initial steep increase in C(m) values lasted approximately 5 to 10 sec. During this time, protoplasts increased in surface area by approximately 2.5%. The biphasic dynamics of [Ca(2)+](cyt)-stimulated increases in C(m) values can be described by a kinetic model containing two pools of vesicles with two [Ca(2)+](cyt)-sensitive steps in the exocytotic pathway.
Original languageEnglish
Pages (from-to)1127-1136
Number of pages10
JournalPlant Cell
Volume12
Issue number7
DOIs
Publication statusPublished - Jul 2000

Keywords

  • membrane capacitance
  • photolysis
  • dimethoxynitrophenamine

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