Panel A: The current traces of hKv1.3 without and with hKCNE4. The x-axis represents time in milliseconds, and the y-axis represents current in picoamperes per picofarad. The presence of hKCNE4 reduces the current. Panel B: A normalized peak current density shows that the x-axis represents time in milliseconds, and the y-axis represents normalized current. KCNE4 accelerates the slow C-type inactivation of Kv1.3. Panel C: A schematic diagram of the KCNE4 regulatory subunit indicates the distal location of the rs12621643 (145D/E) polymorphism. Panel D: A predicted sequence disorder, residue charge, and the transmembrane domain (TMD) of KCNE4. The x-axis represents the sequence from N to C terminus, and the y-axis represents the predicted disorder and residue charge. Blue represents basic (positively charged) residues, and red represents acidic (negatively charged) residues.
Human KCNE4 145D/E polymorphism. (A) Presence of human KCNE4 reduces Kv1.3 currents. HEK293 cells were transfected with hKv1.3 without or with (+) hKCNE4. Currents were elicited with 250-ms-long pulses from −80 mV to +60 mV in 10-mV steps. (B) Normalized peak current density of hKv1.3 in the absence or presence (+) of hKCNE4 at +60 mV. KCNE4 accelerates slow C-type inactivation of Kv1.3. (C) Schematic cartoon of the KCNE4 regulatory subunit with the arrowhead indicating the distal location of the rs12621643 (145D/E) polymorphism. (D) KCNE4 with predicted sequence disorder (top), residue charge (middle), and TMD (orange box) and 145 polymorphism location sequence (bottom). Blue represents basic (positively charged) residues, and red represents acidic (negatively charged) residues.