Fig. 6.

Whole-cell voltage-clamp recordings obtained under conditions of low extracellular calcium concentration. A, C Plots showing one or two exemplary traces of ramps from iRin37 (A) and iRin37-C61,65A (C) cells. iRin37 cells (A) in low external calcium conditions show clear evidence of channel transitions in the V_m range of −20 to −60 mV (observed in two out of ten ramps, one shown), while Cx37-C61,65A-expressing cells (c) show no evidence of channel activity in any ramps in the V_m range −20 to −60 mV (see text for further details). B Transitions of membrane current (corresponding to conductances <400 pS) from single cells expressing Cx37-WT during −30 mV square pulses in low external calcium. Notice that most events appear to be smaller than observed in normal calcium, perhaps revealing more transitions to and from a substate. D Current transitions of Cx37-C61,65A-expressing cells. Notice transitions correspond to events of less than 100 pS. Traces are labeled as in Fig. 5 B, D and F