KCNQ1/KCNE1 assembly, co-translation not required.
Voltage-gated potassium channels are often assembled with accessory proteins that increase their functional diversity. KCNE proteins are small accessory proteins that modulate voltage-gated potassium (K(V)) channels. Although the functional effects of various KCNE proteins have been described, many questions remain regarding their assembly with the pore-forming subunits. For example, while previous experiments with some K(V) channels suggest that the association of the pore-subunit with the accessory subunits occurs co-translationally in the endoplasmic reticulum, it is not known whether KCNQ1 assembly with KCNE1 occurs in a similar manner to generate the medically important cardiac slow delayed rectifier current (I(Ks)). In this study we used a novel approach to demonstrate that purified recombinant human KCNE1 protein (prKCNE1) modulates KCNQ1 channels heterologously expressed in Xenopus oocytes resulting in generation of I(Ks). Incubation of KCNQ1-expressing oocytes with cycloheximide did not prevent I(Ks) expression following prKCNE1 injection. By contrast, incubation with brefeldin A prevented KCNQ1 modulation by prKCNE1. Moreover, injection of the trafficking-deficient KCNE1-L51H reduced KCNQ1 currents. Together, these observations indicate that while assembly of KCNE1 with KCNQ1 does not require co-translation, functional KCNQ1-prKCNE1 channels assemble early in the secretory pathway and reach the plasma membrane via vesicular trafficking.
Vanoye
Carlos G
CG
Department of Medicine, Vanderbilt University, Nashville, TN, USA. carlos.vanoye@vanderbilt.edu
Welch
Richard C
RC
Tian
Changlin
C
Sanders
Charles R
CR
George
Alfred L
AL
D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004721:Endoplasmic Reticulum; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D051657:KCNQ1 Potassium Channel / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D011994:Recombinant Proteins / Q000378:metabolism; D014982:Xenopus laevis
C489622:KCNE1 protein, human; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; D024642:Potassium Channels, Voltage-Gated; D011500:Protein Synthesis Inhibitors; D011994:Recombinant Proteins; D020126:Brefeldin A; D003513:Cycloheximide; D011188:Potassium