The amplitude of quantum bumps in photoreceptors is smaller in animals expressing norpA^C1094S.hs in a norpA³⁶ background than in wild type (when ATP is present in the intracellular solution during recordings).

Patch-clamp whole cell recordings show termination of light-induced currents that is four orders of magnitude slower than wild type in flies carrying norpA^C1094S.hs in a norpA³⁶ background.

Expression is wild type background leads to wild type physiology of ERG recordings. Mutants exhibit long latencies and reduced initial slopes: activation of the visual response is delayed. Following termination of light repolarisation is prolonged. The deactivation waveform of norpA^C1094S.hs inaC² double mutants is similarly delayed as in norpA^C1094S.hs but requires more time to completely repolarise and the latency to activation is almost identical to that of norpA^C1094S.hs. norpA^C1094S.hs inaC² double mutants display a much reduced response to light. norpA^C1094S.hs inaD¹ double mutants display a profound loss of the visual response.