Figure 6.
The main gating mode of CaV2.1 channels lacking the β subunit is a low-po mode different from both the fast and the slow gating modes. Single channel recordings as in Fig. 1 on HEK293 cells transiently coexpressing human CaV2.1α1 (α1A-2) and α2bδ-1 subunits. (A) Consecutive traces at +30 mV from a patch containing a single α1A-2–α2bδ-1 channel. (B) Log–log plots of the open and closed time distributions of the single channel in A. Time constants of the exponential components best fitting the open times: 0.30 and 0.74 ms (relative areas 82 and 18%); time constants for the closed times: 0.69, 11.3, and 34.9 ms (relative areas 31, 36, and 33%). (C) Open probability, po, as a function of voltage for the single channel in A. Fit of the activation curve with a Boltzmann equation gives V1/2 = 44 mV, k = 9.1 mV, po max = 0.46.