Hardie, R.C., Martin, F., Cochrane, G.W., Juusola, M., Georgiev, P., Raghu, P. (2002). Molecular basis of amplification in Drosophila phototransduction. Roles for g protein, phospholipase C, and diacylglycerol kinase.  Neuron 36(4): 689--701.

FBrf0152274

Research paper

In Drosophila photoreceptors, the amplification responsible for generating quantum bumps in response to photoisomerization of single rhodopsin molecules has been thought to be mediated downstream of phospholipase C (PLC), since bump amplitudes were reportedly unaffected in mutants with greatly reduced levels of either G protein or PLC. We now find that quantum bumps in such mutants are reduced approximately 3- to 5-fold but are restored to near wild-type values by mutations in the rdgA gene encoding diacylglycerol kinase (DGK) and also by depleting intracellular ATP. The results demonstrate that amplification requires activation of multiple G protein and PLC molecules, identify DGK as a key enzyme regulating amplification, and implicate diacylglycerol as a messenger of excitation in Drosophila phototransduction.