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CaV channels reject signaling from a second CaM in eliciting Ca2+-dependent feedback regulation.
Chakouri, Nourdine; Diaz, Johanna; Yang, Philemon S; Ben-Johny, Manu.
Afiliação
  • Chakouri N; Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA.
  • Diaz J; Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA.
  • Yang PS; Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
  • Ben-Johny M; Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA. Electronic address: mbj2124@cumc.columbia.edu.
J Biol Chem ; 295(44): 14948-14962, 2020 10 30.
Article em En | MEDLINE | ID: mdl-32820053
Calmodulin (CaM) regulation of voltage-gated calcium (CaV1-2) channels is a powerful Ca2+-feedback mechanism to adjust channel activity in response to Ca2+ influx. Despite progress in resolving mechanisms of CaM-CaV feedback, the stoichiometry of CaM interaction with CaV channels remains ambiguous. Functional studies that tethered CaM to CaV1.2 suggested that a single CaM sufficed for Ca2+ feedback, yet biochemical, FRET, and structural studies showed that multiple CaM molecules interact with distinct interfaces within channel cytosolic segments, suggesting that functional Ca2+ regulation may be more nuanced. Resolving this ambiguity is critical as CaM is enriched in subcellular domains where CaV channels reside, such as the cardiac dyad. We here localized multiple CaMs to the CaV nanodomain by tethering either WT or mutant CaM that lack Ca2+-binding capacity to the pore-forming α-subunit of CaV1.2, CaV1.3, and CaV2.1 and/or the auxiliary ß2A subunit. We observed that a single CaM tethered to either the α or ß2A subunit tunes Ca2+ regulation of CaV channels. However, when multiple CaMs are localized concurrently, CaV channels preferentially respond to signaling from the α-subunit-tethered CaM. Mechanistically, the introduction of a second IQ domain to the CaV1.3 carboxyl tail switched the apparent functional stoichiometry, permitting two CaMs to mediate functional regulation. In all, Ca2+ feedback of CaV channels depends exquisitely on a single CaM preassociated with the α-subunit carboxyl tail. Additional CaMs that colocalize with the channel complex are unable to trigger Ca2+-dependent feedback of channel gating but may support alternate regulatory functions.
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Texto completo: 1 Base de dados: MEDLINE Assunto principal: Calmodulina / Transdução de Sinais / Cálcio / Canais de Cálcio Tipo L Limite: Humans Idioma: En Ano de publicação: 2020 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Calmodulina / Transdução de Sinais / Cálcio / Canais de Cálcio Tipo L Limite: Humans Idioma: En Ano de publicação: 2020 Tipo de documento: Article