Mutational and gene dosage analysis of calcium-activated potassium channels in Drosophila: correlation of micro- and macroscopic currents.
In Drosophila, two Ca2(+)-activated K+ currents, ICF and ICS, have previously been distinguished in conventional voltage clamp experiments. The slowpoke (slo) mutation eliminates ICF specifically. We report that in patch clamp recordings a single-channel Ca2(+)-activated K+ current is readily distinguished from other channel activities in normal larval muscle membrane, whereas no such current is observed in slo muscles. This single-channel current thus correlates with the macroscopic ICF. No obvious differences in amplitude or properties were detected between normal (+/+) and heterozygous (slo/+) ICF channels in whole-cell voltage clamp recordings or single-channel patch clamp recordings. These results are consistent with the hypothesis that slo is a structural gene for the ICF channels only under certain conditions. The selective effect of the slo mutation may reflect a defect in a regulatory mechanism that is specific for the functioning of the ICF channel protein.
Komatsu
A
A
Department of Biology, University of Iowa, Iowa City 52242.
Singh
S
S
Rathe
P
P
Wu
C F
CF
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics*; D004553:Electric Conductivity; D005796:Genes; D009154:Mutation; D015221:Potassium Channels / Q000378:metabolism*
D015221:Potassium Channels; D002118:Calcium