A calcium switch for the functional coupling between alpha (hslo) and beta subunits (KV,Ca beta) of maxi K channels.
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Meera P, Wallner M, Jiang Z, Toro L
A calcium switch for the functional coupling between alpha (hslo) and beta subunits (KV,Ca beta) of maxi K channels.
FEBS Lett. 1996 Mar 11;382(1-2):84-8.
- PubMed ID
- 8612769 [ View in PubMed]
- Abstract
KV,Ca beta subunit dramatically increases the apparent calcium sensitivity of the alpha subunit of MaxiK channels when probed in the micromolar [Ca2+]i range. Analysis in a wide range of [Ca2+]i revealed that this functional coupling is exquisitely modulated by [Ca2+]i. Ca2+ ions switch MaxiK alpha+beta complex into a functionally coupled state at concentrations beyond resting [Ca2+]i. At [Ca2+] < or = 100 nM, MaxiK activity becomes independent of Ca2+, is purely voltage-activated, and its functional coupling with its beta subunit is released. The functional switch develops at [Ca2+]i that occur during cellular excitation, providing the molecular basis of how MaxiK channels regulate smooth muscle excitability and neurotransmitter release.