Role of domain I of neuronal Ca2+ channel alpha1 subunits in G protein modulation

J Physiol. 1998 May 15;509 ( Pt 1)(Pt 1):163-9. doi: 10.1111/j.1469-7793.1998.163bo.x.


1. We studied the G protein inhibition of heteromultimeric neuronal Ca2+ channels by constructing a series of chimeric channels between the strongly modulated alpha1B subunit and the alpha1E(rbEII) subunit, which showed no modulation. 2. In parallel studies, alpha1 subunit constructs were co-expressed together with the accessory Ca2+ channel alpha2-delta and beta2a subunits in mammalian (COS-7) cells and Xenopus oocytes. G protein inhibition of expressed Ca2+ channel currents was induced by co-transfection of Gbeta1 and Ggamma2 subunits in COS-7 cells or activation of co-expressed dopamine (D2) receptors by quinpirole (100 nM) in oocytes. 3. The data indicate that transfer of the alpha1B region containing the N-terminal, domain I and the I-II loop (i.e. the alpha1B1-483 sequence), conferred G protein modulation on alpha1E(rbEII), both in terms of a slowing of activation kinetics and a reduction in current amplitude. 4. In contrast, the data are not consistent with the I-II loop and/or the C-terminal forming a unique site for G protein modulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channels / genetics
  • Calcium Channels / metabolism
  • Calcium Channels / physiology*
  • Cattle
  • Cell Line
  • Electric Stimulation
  • Electrophysiology
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / physiology*
  • Membrane Potentials / physiology
  • Molecular Sequence Data
  • Neurons / physiology*
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Rabbits
  • Rats
  • Transfection
  • Xenopus laevis


  • Calcium Channels
  • GTP-Binding Proteins

Associated data

  • GENBANK/D14157
  • GENBANK/L15453
  • GENBANK/M13236
  • GENBANK/M37183
  • GENBANK/M80545
  • GENBANK/M86621
  • GENBANK/U73901
  • GENBANK/X77458