Characterization of endogenous sodium channel gene expressed in Chinese hamster ovary cells.
Chinese hamster ovary (CHO-K1) cells were observed to display transient inward Na+ currents of average amplitude (-92 +/- 20 pA), which activated at voltages more than -40 mV, and peak inward currents were observed at potentials equal to or more than +10 mV. Inward Na+ currents in these cells were eliminated after treatment with 500 or 50 nM tetrodotoxin (TTX), whereas 5 nM TTX resulted in 64 +/- 10% inhibition of Na+ current. Using DNA primers designed to bind to the rat brain IIA Na+ channel subtype, we amplified specific polymerase chain reaction (PCR) fragments from CHO-K1 poly-(A)+RNA. The cloning and sequencing of two of these fragments confirmed the presence of an endogenously expressed Na+ channel gene in these cells, which we have termed cho 1. Comparison of the DNA sequence of cho 1 PCR fragments with other known Na+ channel genes indicated a high degree of homology with rat brain Na+ channel subtypes. Northern blots using riboprobes generated from the cho 1 PCR fragments revealed the presence of a specific 9-kb mRNA in these cells. The molecular and electrophysiological data suggest that the cho 1 Na+ channel gene from CHO-K1 cells is closely related to brain-type Na+ channels.
Lalik
P H
PH
Department of Molecular Biology, Sterling Winthrop Pharmaceuticals Research Division, Rensselaer, New York 12144.
Krafte
D S
DS
Volberg
W A
WA
Ciccarelli
R B
RB
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001921:Brain / Q000502:physiology*; D016466:CHO Cells; D003001:Cloning, Molecular / Q000379:methods; D006224:Cricetinae; D004247:DNA / Q000235:genetics*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D011061:Poly A / Q000235:genetics / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D015222:Sodium Channels / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D015222:Sodium Channels; D011061:Poly A; D013779:Tetrodotoxin; D012313:RNA; D004247:DNA