Coexpression of cloned α(1B), β(2a), and α2/δ subunits produces non-inactivating calcium currents similar to those found in bovine chromaffin cells

Anne L. Cahill, Joyce Hurley, Aaron P. Fox

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Chromaffin cells express N-type calcium channels identified on the basis of their high sensitivity to block by ω-conotoxin GVIA (ω-CgTx GVIA). In contrast to neuronal N-type calcium currents that inactivate during long depolarizations and that require negative holding potentials to remove inactivation, many chromaffin cells exhibit N-type calcium channel currents that show little inactivation during maintained depolarizations and that exhibit no decrease in channel availability at depolarized holding potentials. N-type calcium channels are thought to be produced by combination of the pore-forming α(1B) subunit and accessory β and α2/δ subunits. To examine the molecular composition of the non-inactivating N-type calcium channel, we cloned the α(1B) and accessory β(β(1b), β(1c), β(2a), β(2b), and β(3a)) subunits found in bovine chromaffin cells. Expression of the subunits in either Xenopus oocytes or human embryonic kidney 293 cells produced high-threshold calcium currents that were blocked by ω-CgTx GVIA. Coexpression of bovine α(1B) with β(1b), β(1c), β(2b.) or β(3a) produced currents that were holding potential dependent. In contrast, coexpression of bovine α(1B) with β(2a) produced holding potential-independent calcium currents that closely mimicked native non-inactivating currents, suggesting that non-inactivating N-type channels consist of bovine α(1B), α2/δ, and β(2a).

Original languageEnglish (US)
Pages (from-to)1685-1693
Number of pages9
JournalJournal of Neuroscience
Volume20
Issue number5
StatePublished - Mar 1 2000
Externally publishedYes

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N-Type Calcium Channels
Chromaffin Cells
Calcium
Conotoxins
Xenopus
Oocytes
Kidney

Keywords

  • α(1B) subunit
  • β subunits
  • Chromaffin cells
  • N-type Calcium channel
  • Non-inactivating calcium current
  • Voltage-dependent calcium channel

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Coexpression of cloned α(1B), β(2a), and α2/δ subunits produces non-inactivating calcium currents similar to those found in bovine chromaffin cells. / Cahill, Anne L.; Hurley, Joyce; Fox, Aaron P.

In: Journal of Neuroscience, Vol. 20, No. 5, 01.03.2000, p. 1685-1693.

Research output: Contribution to journalArticle

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abstract = "Chromaffin cells express N-type calcium channels identified on the basis of their high sensitivity to block by ω-conotoxin GVIA (ω-CgTx GVIA). In contrast to neuronal N-type calcium currents that inactivate during long depolarizations and that require negative holding potentials to remove inactivation, many chromaffin cells exhibit N-type calcium channel currents that show little inactivation during maintained depolarizations and that exhibit no decrease in channel availability at depolarized holding potentials. N-type calcium channels are thought to be produced by combination of the pore-forming α(1B) subunit and accessory β and α2/δ subunits. To examine the molecular composition of the non-inactivating N-type calcium channel, we cloned the α(1B) and accessory β(β(1b), β(1c), β(2a), β(2b), and β(3a)) subunits found in bovine chromaffin cells. Expression of the subunits in either Xenopus oocytes or human embryonic kidney 293 cells produced high-threshold calcium currents that were blocked by ω-CgTx GVIA. Coexpression of bovine α(1B) with β(1b), β(1c), β(2b.) or β(3a) produced currents that were holding potential dependent. In contrast, coexpression of bovine α(1B) with β(2a) produced holding potential-independent calcium currents that closely mimicked native non-inactivating currents, suggesting that non-inactivating N-type channels consist of bovine α(1B), α2/δ, and β(2a).",
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