Alternative Shaker transcripts express either rapidly inactivating or noninactivating K+ channels.
Two members of the Shaker K+ channel family designated ShA2 and ShD2 were characterized in the Xenopus oocyte expression system. The predicted amino acid sequences of ShA2 and ShD2 differ only in the amino terminus, which is located intracellularly according to the present topological model of K+ channels. The differing amino termini have profound effects on the electrophysiological and pharmacological properties of the K+ channel. Most markedly, the nature of the amino terminus determines whether the K+ channel mediates rapidly inactivating or noninactivating K+ currents. It also affects the 4-aminopyridine, tetraethylammonium, and charybdotoxin sensitivities of the K+ channels. These results suggest that the amino terminus of Shaker proteins affects K+ channel structures on both sides of the membrane.
Lehrstuhl für Biochemie, Ruhr-Universität Bochum, Federal Republic of Germany.
M
M
Stocker
W
W
Stühmer
R
R
Wittka
X
X
Wang
R
R
Müller
A
A
Ferrus
O
O
Pongs
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D018999:Charybdotoxin; D004331:Drosophila melanogaster / Q000235:genetics; D004546:Elapid Venoms / Q000494:pharmacology; D004553:Electric Conductivity; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009865:Oocytes; D010455:Peptides / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D012604:Scorpion Venoms / Q000494:pharmacology; D013329:Structure-Activity Relationship; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014982:Xenopus laevis
D004546:Elapid Venoms; D010455:Peptides; D015221:Potassium Channels; D012333:RNA, Messenger; D012604:Scorpion Venoms; D013757:Tetraethylammonium Compounds; D018999:Charybdotoxin; C008331:mast cell degranulating peptide; D019789:Tetraethylammonium; C020273:dendrotoxin; D015761:4-Aminopyridine