Figure 3.

(A) Original current recordings in an oocyte expressing the W317C mutant of the α1 subunit of rat Na,K-ATPase. The holding membrane potential was kept at −50 mV, except for series of short voltage steps. The effect of MTSET was tested by measuring the K⁺-induced outward current before and after exposure to 250 μM MTSET for 2 min. The reversibility of the effect of MTSET was tested by measuring the K⁺-induced outward current before and after exposure to 10 mM DTT for 2 min. (B) Reversibility of the effect of MTSET. The effect of a reducing agent, dithiotreitol (DTT), was measured as described in the examples above. The bar graphs report that amplitude of the K⁺-activated current after MTSET exposure (2 min, 250 μM) and after subsequent DTT treatment (2 min, 10 mM). The current values are normalized in terms of the current measured under the initial control conditions. The DTT-induced recovery was complete the W317C mutant, but only partial in the E314C, Y315C, and I233C mutants. There were between five and seven measurements for each condition. Error bars represent the SEM.