Dr-VSP and pseudojanin can inhibit PI(4,5)P2-sensitive Kir2.1 channels. (A) Currents in Kir2.1 channels coexpressed with Dr-VSP. Black indicates current trace before activation of Dr-VSP, and red indicates current trace 60 ms after activation of Dr-VSP by a 2-s pulse to 100 mV. Hyperpolarizing test pulse protocol is shown above the traces. (B) Inhibition of Kir2.1-mediated currents by activation of Dr-VSP (n = 5). (C) Currents with coexpression of Kir2.1, pseudojanin (PJ)-YFP, and LDR-CFP recorded with the protocol shown in A. Black trace shows steady-state current over time, and the red trace is FRET ratio between pseudojanin-YFP and LDR-CFP. (D) Same experiment as in C but with expression of KV7.2 and KV7.3 as well as Kir2.1. Black trace shows KV7.2/KV7.3-mediated tail currents, and red trace shows Kir2.1-mediated steady-state current over time. (E) Current traces and pulse protocol for the recording shown in D. Black trace shows currents at start of rapamycin (rap.) application (60 s), and red trace is at 900 s (end of recording). (F) Time needed to decrease either KV7.2/KV7.3 or Kir2.1-mediated currents from 90 to 10% original amplitude (n = 4). (B and F) Error bars represent ±SEM.
