FIGURE 4.

Current families, I–V, and kinetics characteristics of channels originated by coinjections of dimeric constructs. Ionic currents elicited by voltage steps from 0 mV to −240 mV in −20 mV decrements from a holding potential of 0 mV, in oocytes coinjected with the following tandem constructs at 1:1 weight ratio: (A) KAT1-KAT1 and KDC1-KAT1 (coinjection a); (B) KAT1-KAT1 and KDC1-KDC1 (coinjection b); and (C) KDC1-KDC1 and KDC1-KAT1 (coinjection c). (D) Current voltage characteristics of the current families shown in panels A–C, normalized with respect to the current at −240 mV. (E) Open-probability versus applied potential for the coexpressed dimers (mean ± SE, N ≥ 6); continuous lines are the best fits with the Boltzmann equation of data from coinjections a–c; dashed line represents the homomeric KAT1-KAT1 channel and dotted line (indicated by the arrow) represents the currents mediated by KDC1-KAT1 channels (case d1); the inset shows a magnification of the Boltzmann curves for coinjections b and c and KDC1-KAT1 channels. (F) Half-activation times, t_1/2, of ionic currents plotted as a function of the membrane voltage. The symbols are the same as in panel D. Also, in this panel, the dashed line represents the half-activation times obtained from the homomeric KAT1-KAT1 tandem construct, while the dotted line corresponds to times produced by the KDC1-KAT1 dimer.