The KCNE1 beta-subunit exerts a transient effect on the KCNQ1 K+ channel.
The KCNE1 beta-subunit is a modulatory one-trans-membrane segment accessory protein that alters KCNQ1 K(+) channel current characteristics, though it is not required for channel expression. The KCNE1 and KCNQ1 interaction was investigated by looking for effects of expression time on channel currents in Xenopus laevis oocytes. We found that long-time expression of KCNQ1+KCNE1 (2-14 days) resulted in gradual changes in current characteristics resembling a disappearance of KCNE1 from the oocyte plasma membrane. Towards the end of the expression period the current of oocytes expressing KCNQ1+KCNE1 was indistinguishable from those expressing KCNQ1 alone. No time dependent effect was seen in oocytes expressing KCNQ1 alone or a concatamer of KCNQ1 and KCNE1. Brefeldin A was tested, showing that measured current was independent of exocytosis (decreased capacitance) thus eliminating a continuous displacement-explanation. Based on the functional data, we suggest that the interaction between KNCE1 and KCNQ1 may be reversible and transient in a "Kiss & Go" manner, supporting a physiological role for KCNE1 as a dynamic regulatory molecule.
Poulsen
Asser Nyander
AN
Department of Physiology and Biochemistry, IBHV, Faculty of Life Sciences, University of Copenhagen, Groennegaardsvej 7, 1870 Frederiksberg C, Denmark. aspo@life.ku.dk
Klaerke
Dan Arne
DA
D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D015640:Ion Channel Gating / Q000502:physiology*; D051657:KCNQ1 Potassium Channel / Q000737:chemistry / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology*; D009865:Oocytes / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D021122:Protein Subunits; D014982:Xenopus laevis
C489622:KCNE1 protein, human; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; D024642:Potassium Channels, Voltage-Gated; D021122:Protein Subunits