Binding of G alpha(o) N terminus is responsible for the voltage-resistant inhibition of alpha(1A) (P/Q-type, Ca(v)2.1) Ca(2+) channels.
G-protein-mediated inhibition of presynaptic voltage-dependent Ca(2+) channels is comprised of voltage-dependent and -resistant components. The former is caused by a direct interaction of Ca(2+) channel alpha(1) subunits with G beta gamma, whereas the latter has not been characterized well. Here, we show that the N terminus of G alpha(o) is critical for the interaction with the C terminus of the alpha(1A) channel subunit, and that the binding induces the voltage-resistant inhibition. An alpha(1A) C-terminal peptide, an antiserum raised against G alpha(o) N terminus, and a G alpha(o) N-terminal peptide all attenuated the voltage-resistant inhibition of alpha(1A) currents. Furthermore, the N terminus of G alpha(o) bound to the C terminus of alpha(1A) in vitro, which was prevented either by the alpha(1A) channel C-terminal or G alpha(o) N-terminal peptide. Although the C-terminal domain of the alpha(1B) channel showed similar ability in the binding with G alpha(o) N terminus, the above mentioned treatments were ineffective in the alpha(1B) channel current. These findings demonstrate that the voltage-resistant inhibition of the P/Q-type, alpha(1A) channel is caused by the interaction between the C-terminal domain of Ca(2+) channel alpha(1A) subunit and the N-terminal region of G alpha(o).
Kinoshita
M
M
Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Nukada
T
T
Asano
T
T
Mori
Y
Y
Akaike
A
A
Satoh
M
M
Kaneko
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020864:Calcium Channels, N-Type / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D005260:Female; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010053:Ovary / Q000502:physiology; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D014982:Xenopus laevis
D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins; D010446:Peptide Fragments; D010455:Peptides; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins