Fig. 1. Effect of N- and C–terminal deletions on expression of KvLQT1 currents in Xenopus oocytes. (A) Diagram illustrating KvLQT1 constructs used for heterologous expression of cRNA in Xenopus oocytes. Two KvLQT1 cDNA versions encoding full-length KvLQT1 and a shorter (sKvLQT1) ORF have been reported (Sanguinetti et al., 1996; Yang et al., 1997). Grey boxes indicate putative transmembrane regions S1–S6; P refers to the P–domain being involved in pore formation. Numbers in deletion constructs refer to amino acid residues of full-length KvLQT1 protein. (B) Currents measured after injection of cRNA encoding KvLQT1, sKvLQT1 and KvLQT1Δ1–127, respectively. (C) Currents were measured after injection of cRNA encoding, sKvLQT1Δ651–676, sKvLQT1Δ621–676 and sKvLQT1Δ590–676. (D) Data pooled from a number of oocytes (n = 6–28) including the constructs illustrated in (A) and an H2O control. The 100% Irel value corresponds to the steady-state current amplitude of sKvLQT1 after a 4 s test pulse to +40 mV.