Fig. 4: SMIT1–KCNQ complexes KCNQ-isoform dependently distinguish between GABA and related metabolites.
From: Potassium channels act as chemosensors for solute transporters
All error bars indicate SEM. a Mean traces showing currents generated by KCNQ3* alone or with SMIT1 (n = 8). b Mean peak currents for KCNQ3* alone (black) or with SMIT1 (red) quantified from traces as in (a) (n = 8). c Mean peak tail currents for KCNQ3* alone (black) or with SMIT1 (red) quantified from traces as in (a) (n = 8). d Mean G/Gmax relationship for KCNQ3* alone (black) or with SMIT1 (red) quantified from traces as in (a) (n = 8). e Effects of SMIT1 on KCNQ3* activation rate quantified as a single exponential fit, time constant = τact (n = 8). *p < 0.05. f Mean EM of unclamped oocytes expressing KCNQ3* alone (black) or with SMIT1 (red) (n = 8). *p < 0.05. g Representative traces from KCNQ2 (Q2) in 100 mM K+ (voltage protocol inset). h Mean current–voltage relationship for Q2 in 100 mM K+ (black), Cs+ (blue), Rb+ (red), and Na+ (magenta), in the absence or presence of SMIT1 as indicated; quantified from traces as in (g); n = 5. i Estimated mean permeability relative to that of K+ versus ionic radius (Pauling) through Q2 in the absence (black) and presence (blue) of SMIT1; n = 5. *p < 0.05; **p < 0.01. j Representative traces from KCNQ3* (Q3*) in 100 mM K+ (voltage protocol as in (g)). k Mean current–voltage relationship for Q3* in 100 mM K+ (black), Cs+ (blue), Rb+ (red), and Na+ (magenta), with/without SMIT1 as indicated; quantified from traces as in (j); n = 4. l Estimated mean permeability relative to that of K+ versus ionic radius (Pauling) through Q3* with (red) or without (black) SMIT1; n = 4. **p = 0.006. m [3H]Myo-inositol uptake (30 min) for oocytes expressing KCNQ2 and SMIT1 in the absence or presence of neurotransmitters/metabolites indicated (100 µM) ([3H]Myo-inositol n = 10; GABA n = 16; BHB n = 17; GABOB n = 13). n [3H]Myo-inositol uptake (30 min) for oocytes expressing KCNQ3* and SMIT1 with/without neurotransmitters/metabolites indicated (100 µM) ([3H]Myo-inositol n = 17; GABA n = 10; BHB n = 8; GABOB n = 16).
