Models for CaV1.3b current inhibition by AA. (A) Schematic for a single channel undergoing different closed conformations before opening. Conformations in deep closed states, like those at −90 mV, may preferentially bind AA. (B) Schematic for whole cell channel populations. Two populations of channels may exist at a given holding potential. At −90 mV, the majority of channels are in RC conformations as opposed to WC conformations. At −60 mV, the majority of channels are in WC conformations. AA preferentially binding RC channels may explain the greater amount of AA inhibition at −90 mV. (C) Hypothetical model for the inhibition of CaV1.3b channels by AA. (Top) CaV1.3b channel with two sites for AA inhibition. (Bottom) The palmitoyl groups of β2a (or excess PA) may occlude one of the sites for AA inhibition.
