I–V relationships of Maxi‐Cl activity recorded after reconstitution of the WT SLCO2A1 (white, blue, and green circles) or the K613G mutant (red circles). Recordings were obtained using normal Ringer solution in the bath and pipettes (white symbols), with normal Ringer solution in the bath and Ringer solution in which all Na
+ ions were replaced with equimolar NMDG
+ in pipettes (blue and red symbols), or under a KCl gradient (green symbols: 150/30 mM pipette/bath supplemented with 1 mM CaCl
2 and 11 mM HEPES–KOH, pH 7.4). Error bars, SEM. For green symbols: The reversal potential for WT SLCO2A1 of −27.3 mV corresponds to P
Cl/P
K = 9.3. The slope conductance for K613G (258 ± 5 pS) is significantly smaller than that for WT (354 ± 4 pS) at
P <
0.05, and its reversal potential slightly shifted in a negative direction (red symbols).
n =
3–15 from five different patches (see
Appendix Table S2 for expression vectors used here.)