Mapping the receptor site for hanatoxin, a gating modifier of voltage-dependent K+ channels.
Hanatoxin (HaTx) binds to multiple sites on the surface of the drk1 voltage-gated K+ channel and modifies channel gating. We set out to identify channel residues that contribute to form these HaTx binding sites. Chimeras constructed using the drk1 and shaker K+ channels suggest that the S3-S4 linker may contain influential residues. Alanine scanning mutagenesis of the region extending from the C terminal end of S3 through S4 identified a number of residues that likely contribute to form the HaTx binding sites. The pore blocker Agitoxin2 and the gating modifier HaTx can simultaneously bind to individual K+ channels. These results suggest that residues near the outer edges of S3 and S4 form the HaTx binding sites and are eccentrically located at least 15 A from the central pore axis on the surface of voltage-gated K+ channels.
Swartz
K J
KJ
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
MacKinnon
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002678:Chimera; D002874:Chromosome Mapping; D004330:Drosophila / Q000235:genetics; D004594:Electrophysiology; D005260:Female; D015640:Ion Channel Gating / Q000187:drug effects*; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000378:metabolism* / Q000494:pharmacology*; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics*; D012604:Scorpion Venoms / Q000378:metabolism; D014118:Toxins, Biological / Q000378:metabolism
D010455:Peptides; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D011956:Receptors, Cell Surface; D012604:Scorpion Venoms; D014118:Toxins, Biological; C096469:hanatoxin; C087603:agitoxin 2