Figure 3. Dominant negative effects of Kir 1.1a 331X on wild-type Kir 1.1a. Ba2+-sensitive inward current is plotted (I/Io, Vm = −90 mV) as a function of Fmut, the mutant fraction of the total cRNA injected [Fmut = nanograms mut cRNA/(nanograms mut cRNA + nanograms wt cRNA)]. Fmut was adjusted by coinjecting variable amounts of Kir 1.1a 331X with a constant dose of Kir 1.1a (250 pg), and Io is the mean current when Fmut = 0. The dotted line (A) represents the predicted relationship if inclusion of one or more mutant subunits within a tetramer inhibits channel function [I/Io = (1 Fmut)4]. The dashed curve (B) is predicted if two or more subunits are required [I/Io = (1 − Fmut)4 + 4(1 − Fmut)3Fmut]. The data are best fit by an intermediate model, I/Io = (1 − 0.6 Fmut)4, represented by the solid line (C). The coefficient, k, is less than unity, indicating that a single mutant subunit partially inhibits current or that Kir 1.1a331X oligomerizes with a reduced efficiency.
Image published in: Flagg TP et al. (1999)
© 1999 The Rockefeller University Press. Creative Commons Attribution-NonCommercial-ShareAlike license
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