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Modulation of the ER Ca 2+ channel BCC1 from tendrils of Bryonia dioica by divalent cations, protons and H 2 O 2
Author(s) -
Klüsener Birgit,
Boheim Günther,
Weiler Elmar W
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00364-5
Subject(s) - chemistry , divalent , conductance , biophysics , cytosol , tendril , inorganic chemistry , crystallography , biochemistry , enzyme , botany , mathematics , organic chemistry , combinatorics , biology
Electrical properties of the ER Ca 2+ channel BCC1 from tendrils of Bryonia dioica were analyzed after incorporation of BCC1 into black lipid bilayers. Single channel current fluctuations were modulated by divalent cations, protons and H 2 O 2 . Whereas the channel is permeable for Ca 2+ , Ba 2+ and Sr 2+ , its conductance is strongly reduced in solutions containing MgCl 2 . Cu 2+ and Zn 2+ are potent inhibitors of BCC1 in micromolar concentrations. The open channel conductance of BCC1 increases with acidification of the electrolyte solution. H 2 O 2 shows strong inhibitory effects on BCC1. The channel is almost completely closed at submillimolar concentrations of H 2 O 2 . The effects of pH and H 2 O 2 on channel properties are directional and affect BCC1 at the Ca exit side, but not on the entry site. Thus, cytosolic pH and H 2 O 2 levels may play an important role in the modulation of the cytoplasmic free calcium concentration through BCC1.