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A calcium switch for the functional coupling between α ( hslo ) and β subunits (K V , Ca β ) of maxi K channels
Author(s) -
Meera P,
Wallner M,
Jiang Z,
Toro L
Publication year - 1996
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 - 10.1016/0014-5793(96)00151-2
Subject(s) - chemistry , coupling (piping) , calcium , excitation–contraction coupling , biophysics , physics , materials science , biology , organic chemistry , metallurgy
K V , Ca β subunit dramatically increases the apparent calcium sensitivity of the α subunit of MaxlK channels when probed in the micromolar [Ca 2+ ] i range. Analysis in a wide range of [Ca 2+ ] i revealed that this functional coupling is exquisitely modulated by [Ca 2+ ] i . Ca 2+ ions switch MaxiK α + β complex into a functionally coupled state at concentrations beyond resting [Ca 2+ ] i . At [Ca 2+ ] ≤ 100 nM, MaxiK activity becomes independent of Ca 2+ , is purely voltage‐activated, and its functional coupling with its β subunit is released. The functional switch develops at [Ca 2+ ] i that occur during cellular excitation, providing the molecular basis of how MaxiK channels regulate smooth muscle excitability and neurotransmitter release.