A calcium switch for the functional coupling between α ( hslo) and β subunits (K V , Ca β) of maxi K channels
Abstract
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.
- Publication:
-
FEBS Letters
- Pub Date:
- January 1996
- DOI:
- 10.1016/0014-5793(96)00151-2
- Bibcode:
- 1996FEBSL.382...84M
- Keywords:
-
- MaxiK channel;
- Calcium-independent activation;
- Calcium-dependent activation;
- Human myometrium;
- Subunit interaction α-β