Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltage

Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltage

Large conductance Ca2+-activated K+ (BK) channels belong to the S4 superfamily of K+ channels that include voltage-dependent K+ (Kv) channels characterized by having six (S1-S6) transmembrane domains and a positively charged S4 domain. As Kv channels, BK channels contain a S4 domain, but they have a...

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Autores principales: LATORRE,RAMÓN, BRAUCHI,SEBASTIAN
Lenguaje:English
Publicado: Sociedad de Biología de Chile 2006
Materias:
BK channel
Ca2+-binding sites
voltage dependence
allosteric models
Acceso en línea:http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000300003
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spelling oai:scielo:S0716-976020060003000032014-01-24Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltageLATORRE,RAMÓNBRAUCHI,SEBASTIAN BK channel Ca2+-binding sites voltage dependence allosteric models Large conductance Ca2+-activated K+ (BK) channels belong to the S4 superfamily of K+ channels that include voltage-dependent K+ (Kv) channels characterized by having six (S1-S6) transmembrane domains and a positively charged S4 domain. As Kv channels, BK channels contain a S4 domain, but they have an extra (S0) transmembrane domain that leads to an external NH2-terminus. The BK channel is activated by internal Ca2+, and using chimeric channels and mutagenesis, three distinct Ca2+-dependent regulatory mechanisms with different divalent cation selectivity have been identified in its large COOH-terminus. Two of these putative Ca2+-binding domains activate the BK channel when cytoplasmic Ca2+ reaches micromolar concentrations, and a low Ca2+ affinity mechanism may be involved in the physiological regulation by Mg2+. The presence in the BK channel of multiple Ca2+-binding sites explains the huge Ca2+ concentration range (0.1 μM-100 μM) in which the divalent cation influences channel gating. BK channels are also voltage-dependent, and all the experimental evidence points toward the S4 domain as the domain in charge of sensing the voltage. Calcium can open BK channels when all the voltage sensors are in their resting configuration, and voltage is able to activate channels in the complete absence of Ca2+. Therefore, Ca2+ and voltage act independently to enhance channel opening, and this behavior can be explained using a two-tiered allosteric gating mechanism.info:eu-repo/semantics/openAccessSociedad de Biología de ChileBiological Research v.39 n.3 20062006-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000300003en10.4067/S0716-97602006000300003
institution Scielo Chile
collection Scielo Chile
language English
topic BK channel
Ca2+-binding sites
voltage dependence
allosteric models
spellingShingle BK channel
Ca2+-binding sites
voltage dependence
allosteric models
LATORRE,RAMÓN
BRAUCHI,SEBASTIAN
Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltage
description Large conductance Ca2+-activated K+ (BK) channels belong to the S4 superfamily of K+ channels that include voltage-dependent K+ (Kv) channels characterized by having six (S1-S6) transmembrane domains and a positively charged S4 domain. As Kv channels, BK channels contain a S4 domain, but they have an extra (S0) transmembrane domain that leads to an external NH2-terminus. The BK channel is activated by internal Ca2+, and using chimeric channels and mutagenesis, three distinct Ca2+-dependent regulatory mechanisms with different divalent cation selectivity have been identified in its large COOH-terminus. Two of these putative Ca2+-binding domains activate the BK channel when cytoplasmic Ca2+ reaches micromolar concentrations, and a low Ca2+ affinity mechanism may be involved in the physiological regulation by Mg2+. The presence in the BK channel of multiple Ca2+-binding sites explains the huge Ca2+ concentration range (0.1 μM-100 μM) in which the divalent cation influences channel gating. BK channels are also voltage-dependent, and all the experimental evidence points toward the S4 domain as the domain in charge of sensing the voltage. Calcium can open BK channels when all the voltage sensors are in their resting configuration, and voltage is able to activate channels in the complete absence of Ca2+. Therefore, Ca2+ and voltage act independently to enhance channel opening, and this behavior can be explained using a two-tiered allosteric gating mechanism.
author LATORRE,RAMÓN
BRAUCHI,SEBASTIAN
author_facet LATORRE,RAMÓN
BRAUCHI,SEBASTIAN
author_sort LATORRE,RAMÓN
title Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltage
title_short Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltage
title_full Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltage
title_fullStr Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltage
title_full_unstemmed Large conductance Ca2+-activated K+ (BK) channel: Activation by Ca2+ and voltage
title_sort large conductance ca2+-activated k+ (bk) channel: activation by ca2+ and voltage
publisher Sociedad de Biología de Chile
publishDate 2006
url http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000300003
work_keys_str_mv AT latorreramon largeconductanceca2activatedkbkchannelactivationbyca2andvoltage
AT brauchisebastian largeconductanceca2activatedkbkchannelactivationbyca2andvoltage
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