Modulation of gating currents of the Ca(v)3.1 calcium channel by alpha 2 delta 2 and gamma 5 subunits.
Modulatory effects of auxiliary alpha(2)delta(2) and gamma(5) subunits on intramembrane charge movement originating from the expressed Ca(v)3.1 calcium channel were investigated. Inward current was blocked by 1mM La(3+). Voltage dependences of Q(on) and Q(off), kinetics of ON- and OFF-charge movement, and I(max)/Q(max) ratio were measured in the absence and the presence of an auxiliary subunit. The alpha(2)delta(2) subunit accelerated significantly both ON- and OFF-charge movement. I(max)/Q(max) ratio and Q(on)-V, Q(off)-V relations were not affected. Coexpression of the alpha(2)delta(2) subunit may accelerate channel transitions between individual closed states, but not the transition from the last closed channel state into an open state. Coexpression of the gamma(5) subunit accelerated the decay of the ON-charge transient and enhanced I(max)/Q(max) ratio. These effects suggest improvement of the coupling between the charge movement and the channel opening due to facilitation of transitions between individual closed states and the transition between the last closed state and an open state.
Lacinová
Lubica
L
Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlárska 5, Bratislava 833 04, Slovakia.
Klugbauer
N
N
D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D020747:Calcium Channels, T-Type / Q000187:drug effects / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D007811:Lanthanum / Q000494:pharmacology; D008564:Membrane Potentials / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism
C121855:CACNA1G protein, human; C480968:CACNA2D2 protein, human; D015220:Calcium Channels; D020747:Calcium Channels, T-Type; D011994:Recombinant Proteins; D007811:Lanthanum