Inactivating properties of recombinant ROMK2 channels expressed in mammalian cells.
Biophysical properties of ROMK2 channel were investigated at physiological temperature, after reexpression of the recombinant ROMK2 protein in a mammalian cell expression system (COS-7). We observed that ROMK2 induced an inwardly rectifying K(+) current whether polyvalent cations were present or not. Above +10 mV, ROMK2-induced current exhibited a voltage- and time-dependent decay, consistent with an inactivation process. Inactivation of ROMK2-induced current was also seen in inside out patch from ROMK2-expressing Xenopus oocyte. In COS-7 cells, inactivation was found to account for most of the inward rectification. Mg(2+) and spermine modulated rectification by accelerating inactivation kinetics independently of membrane potential. These results establish for the first time ROMK2 properties in a mammalian cell expression system.
Riochet
D F
DF
Laboratoire de Physiopathologie et de Pharmacologie Cellulaires et Moléculaires, INSERM U533, Hôtel Dieu, Nantes, 44093, France.
Mohammad-Panah
R
R
Hebert
S C
SC
MacGregor
G G
GG
Baró
I
I
Guihard
G
G
Escande
D
D
D000818:Animals; D019556:COS Cells; D004553:Electric Conductivity; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008564:Membrane Potentials; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics / Q000502:physiology*; D024661:Potassium Channels, Inwardly Rectifying; D011994:Recombinant Proteins / Q000378:metabolism; D013095:Spermidine / Q000494:pharmacology; D014162:Transfection; D014981:Xenopus
D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011994:Recombinant Proteins; D008274:Magnesium; D013095:Spermidine