Influence of γ
VDCC currents expressed in Xenopus oocytes. A The peak current-voltage relationships for CaV2.1/β4 (n = 16), CaV2.1/β4/γ2 (n = 14) and CaV2.1/β4/γ4 (n = 11) show no significant differences in any parameters (Table 1). The bottom panels display representative traces recorded from a single oocyte injected with each subunit combination investigated. B. The peak current-voltage relationships for CaV2.1/β4/α2δ2 (n = 43), CaV2.1/β4/α2δ2/γ2 (n = 34) and CaV2.1/β4/α2δ2/γ4 (n = 20) show no significant differences in any parameters (Table 1). In both panels A and B, only representative traces from -50 to +10 mV are displayed for reasons of clarity. C. Mean steady state inactivation data for IBa recorded in 10 mM Ba2+ from Xenopus oocytes injected with CaV2.1/β4/α2δ2 (n = 18) or CaV2.1/β4/α2δγ (n = 18) D. CaV2.1/β4/α2δ2 (n = 20), or CaV2.1/β4/α2δ2/γ4 (n = 20). Co-expression of either γ2 or γ4 produced data almost identical to the control. E. Oocytes injected with CaV2.1/β4 (n = 22), CaV2.1/β4γ2 (n = 16) and CaV2.1/β4γ4 (n = 9) normalized to the maximum current Imax and fitted with a single Boltzmann function. The numerical data for parameters defining the steady-state inactivation relationships are displayed in Table 2.