Decay of prepulse facilitation of N type calcium channels during G protein inhibition is consistent with binding of a single G βγ subunit
Year: 1998
Type: article
Abstract: We have examined the modulation of cloned and stably expressed rat brain N type calcium channels (alpha1B + beta1b + alpha2delta subunits) by exogenously applied purified G protein betagamma subunits. In the absence of Gbetagamma, barium currents through N type channels are unaffected by application of strong depolarizing prepulses. In contrast, inclusion of purified Gbetagamma in the patch pipette results in N type currents that initially facilitated upon application of positive prepulses followed by rapid reinhibition. Examination of the kinetics of Gbetagamma-dependent reinhibition showed that as the duration between the test pulse and the prepulse was increased, the degree of facilitation was attenuated in a monoexponential fashion. The time constant tau for the recovery from facilitation was sensitive to exogenous Gbetagamma, so that the inverse of tau linearly depended on the Gbetagamma concentration. Overall, the data are consistent with a model whereby a single Gbetagamma molecule dissociates from the channel during the prepulse, and that reassociation of Gbetagamma with the channel after the prepulse occurs as a bimolecular reaction.
Authors: Gerald W. Zamponi, Terry P. Snutch
Institutions: University of British Columbia, University of Calgary
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2108621079