Restoration of inactivation in mutants of Shaker potassium channels by a peptide derived from ShB.
Site-directed mutagenesis experiments have suggested a model for the inactivation mechanism of Shaker potassium channels from Drosophila melanogaster. In this model, the first 20 amino acids form a cytoplasmic domain that interacts with the open channel to cause inactivation. The model was tested by the internal application of a synthetic peptide, with the sequence of the first 20 residues of the ShB alternatively spliced variant, to noninactivating mutant channels expressed in Xenopus oocytes. The peptide restored inactivation in a concentration-dependent manner. Like normal inactivation, peptide-induced inactivation was not noticeably voltage-dependent. Trypsin-treated peptide and peptides with sequences derived from the first 20 residues of noninactivating mutants did not restore inactivation. These results support the proposal that inactivation occurs by a cytoplasmic domain that occludes the ion-conducting pore of the channel.
Zagotta
W N
WN
Department of Molecular and Cellular Physiology, Stanford University School of Medicine, CA 94305.
Hoshi
T
T
Aldrich
R W
RW
D000595:Amino Acid Sequence; D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics*; D004553:Electric Conductivity; D006358:Hot Temperature; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D013329:Structure-Activity Relationship; D014357:Trypsin / Q000494:pharmacology; D014981:Xenopus
D010446:Peptide Fragments; D015221:Potassium Channels; D014357:Trypsin