Figure 1. Physical association of HERG with KCNE1 and KCNE2.

(A) Immunoblots of HERG-myc and FLAG-KCNE proteins co-transfected into HEK cells stably expressing HERG. Top gels show HERG and endogenous tubulin as a loading control. Lower gels show immunoblots of KCNE proteins from cell lysates (IB-KCNE/(FLAG)) and of KCNE that co-precipitated with HERG (IP-myc/IB-FLAG). (B) Densitometry analysis of efficiency of association of KCNEs with HERG expressed as amount of KCNE co-precipitated divided by the total amount of KCNE in the cells [KCNE-IP/(KCNE from cell lysates/tubulin)] (for comparison, results were normalized to 1 for KCNE2). (**: p<0.005, n = 3). (C) Metabolic labeling of HERG with ³⁵S and pulse-chase from cells co-transfected with either GFP as control (top gel), KCNE1 (middle gel) or KCNE2 (lower gel). (D) Densitometry analysis of pulse chase (normalized to maximum label intensity within experiment). Left panel shows time course of appearance and disappearance of the higher molecular weight mature form of HERG. Right panel shows time course of disappearance of lower molecular weight immature form of HERG (n = 4).