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Role of domain I of neuronal Ca 2+ channel α1 subunits in G protein modulation
Author(s) -
Stephens Gary J.,
Cantí Carles,
Page Karen M.,
Dolphin Annette C.
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.163bo.x
Subject(s) - xenopus , protein subunit , quinpirole , g protein , biophysics , transfection , biology , fusion protein , chemistry , c terminus , microbiology and biotechnology , receptor , dopamine receptor , biochemistry , recombinant dna , gene , amino acid
1 We studied the G protein inhibition of heteromultimeric neuronal Ca 2+ channels by constructing a series of chimeric channels between the strongly modulated α1B subunit and the α1E(rbEII) subunit, which showed no modulation. 2 In parallel studies, α1 subunit constructs were co‐expressed together with the accessory Ca 2+ channel α2‐δ and β2a subunits in mammalian (COS‐7) cells and Xenopus oocytes. G protein inhibition of expressed Ca 2+ channel currents was induced by co‐transfection of Gβ1 and Gγ2 subunits in COS‐7 cells or activation of co‐expressed dopamine (D2) receptors by quinpirole (100 n m ) in oocytes. 3 The data indicate that transfer of the α1B region containing the N‐terminal, domain I and the I‐II loop (i.e. the α1B 1‐483 sequence), conferred G protein modulation on α1E(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.