The membrane potential effects on Ca2+ current under fixed voltage. (A) The relationship between membrane potential and intraciliary Ca2+ concentration is shown under voltage clamp conditions. (B) The inward current amplitude dependence as a function of a fast shift in the holding membrane potential. Calculations were performed for different concentrations of Ca2+ sensor protein, CaC0. The model predicts qualitatively similar responses for a relatively wide range of Cac0 concentrations.