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Clathrin‐mediated endocytosis in snake motor terminals is directly facilitated by intracellular Ca 2+
Author(s) -
Teng Haibing,
Wilkinson Robert S.
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2005.087296
Subject(s) - endocytosis , exocytosis , receptor mediated endocytosis , biophysics , chemistry , ionophore , intracellular , stimulation , microbiology and biotechnology , biochemistry , biology , endocrinology , cell , membrane
At the snake neuromuscular junction, low temperature (LT, 5–7°C) blocks clathrin‐mediated endocytosis (CME) while exocytosis is largely unaffected. Thus compensatory endocytosis that normally follows transmitter release is inhibited, or ‘delayed’ until the preparation is warmed to room temperature (RT). This delay was exploited to observe how changes in bulk [Ca 2+ ] i directly affect CME. Motor terminals were loaded with fura‐2 to monitor [Ca 2+ ] i . With brief stimulation at LT, [Ca 2+ ] i transiently increased but returned to baseline (∼63 n m ) in < 8 min. After 15 min at LT, [Ca 2+ ] i was altered by incubating preparations in the Ca 2+ ionophore ionomyocin. Preparations were then warmed to RT to initiate delayed endocytosis, which was quantified as uptake of the fluorescent optical probe sulforhodamine 101. Endocytosis was more rapid when [Ca 2+ ] i increased; the rate at 300 n m Ca 2+ was ∼double that under basal conditions. Thus the rate of CME – isolated from stimulation, transmitter release, and other forms of endocytosis – is directly influenced by intraterminal Ca 2+ .