Toxin and kinetic profile of rat brain type III sodium channels expressed in Xenopus oocytes.
Sodium (Na+) channels are members of a multigene family and are responsible for generation and propagation of the action potential in excitable cells. We have assembled, in a transcription-competent vector, a full-length cDNA clone encoding the rat brain type III Na+ channel. Xenopus oocytes microinjected with in vitro synthesized mRNA expressed functional rat brain Na+ channels from such 'cloned' RNA transcripts. We found that type III Na+ currents in whole cell microelectrode voltage clamp and in cell-attached patch recordings decayed much more slowly than any other reported Na+ current. In addition, we saw typical and additive effects of alpha- and beta-scorpion toxins, suggesting that the Na+ channel alpha-subunit itself contains functional and distinct toxin binding sites.
Joho
R H
RH
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030.
Moorman
J R
JR
VanDongen
A M
AM
Kirsch
G E
GE
Silberberg
H
H
Schuster
G
G
Brown
A M
AM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004558:Electric Stimulation; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012604:Scorpion Venoms / Q000494:pharmacology*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D014982:Xenopus laevis
D009498:Neurotoxins; D012333:RNA, Messenger; D012604:Scorpion Venoms; D015222:Sodium Channels; D004247:DNA