Novel potassium channels encoded by the Shaker locus in Drosophila photoreceptors.
The Shaker gene, responsible for A-type potassium channels in Drosophila muscle, encodes a large family of transcripts capable of generating a variety of kinetically distinct A channels when expressed in oocytes. We describe a distinct class of A channel encoded by the Shaker gene in a novel preparation of dissociated Drosophila photoreceptors. Whole-cell recordings reveal a rapidly inactivating A current that is absent in Shaker mutants and that can be readily isolated in cell-attached patches. Although very similar to their muscle counterparts, the photoreceptor A channels show a striking 40-50 mV negative shift in their voltage-operating range. Two mutations (ShE62 and T(1;Y)W32), which exclude only certain classes of Shaker transcripts, were used to show that photoreceptor A channels are encoded by multiple transcripts distinct from those encoding muscle A channels, while PCR techniques identified four transcripts (ShA1, ShA2, ShG1, and ShG2) in mRNA from dissected retina.
Hardie
R C
RC
Cambridge University, Department of Zoology, England.
Voss
D
D
Pongs
O
O
Laughlin
S B
SB
D000818:Animals; D004247:DNA / Q000235:genetics; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D004553:Electric Conductivity / Q000502:physiology; D005796:Genes / Q000235:genetics* / Q000502:physiology; D009132:Muscles / Q000502:physiology / Q000648:ultrastructure; D010786:Photoreceptor Cells / Q000502:physiology / Q000648:ultrastructure*; D016133:Polymerase Chain Reaction; D015221:Potassium Channels / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D014158:Transcription, Genetic / Q000235:genetics*
D015221:Potassium Channels; D004247:DNA