KCNE1 subunits require co-assembly with K+ channels for efficient trafficking and cell surface expression.
KCNE peptides are a class of type I transmembrane beta subunits that assemble with and modulate the gating and ion conducting properties of a variety of voltage-gated K(+) channels. Accordingly, mutations that disrupt the assembly and trafficking of KCNE-K(+) channel complexes give rise to disease. The cellular mechanisms responsible for ensuring that KCNE peptides assemble with voltage-gated K(+) channels have yet to be elucidated. Using enzymatic deglycosylation, immunofluorescence, and quantitative cell surface labeling experiments, we show that KCNE1 peptides are retained in the early stages of the secretory pathway until they co-assemble with specific K(+) channel subunits; co-assembly mediates KCNE1 progression through the secretory pathway and results in cell surface expression. We also address an apparent discrepancy between our results and a previous study in human embryonic kidney cells, which showed wild type KCNE1 peptides can reach the plasma membrane without exogenously expressed K(+) channel subunits. By comparing KCNE1 trafficking in three cell lines, our data suggest that the errant KCNE1 trafficking observed in human embryonic kidney cells may be due, in part, to the presence of endogenous voltage-gated K(+) channels in these cells.
Chandrasekhar
Kshama D
KD
Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
Bas
Tuba
T
Kobertz
William R
WR
D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006224:Cricetinae; D004721:Endoplasmic Reticulum / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D006056:Golgi Apparatus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D021122:Protein Subunits / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D053484:RecQ Helicases / Q000378:metabolism
C489622:KCNE1 protein, human; D024642:Potassium Channels, Voltage-Gated; D021122:Protein Subunits; D053484:RecQ Helicases