CDP-diacylglycerol synthase (CDS) is an enzyme required for the regene
ration of the signalling molecule phosphatidylinositol-4,5-bisphosphat
e (PtdlnsP(2)) from phosphatidic acid. A photoreceptor cell-specific i
soform of CDS from Drosophila is a key regulator of phototransduction,
a G-protein-coupled signalling cascade mediated by phospholipase C, c
ds mutants cannot sustain a light-activated current as a result of dep
letion of PtdlnsP(2). Overexpression of CDS increases the amplitude of
the light response, demonstrating that availability of PtdlnsP(2) is
a determinant in the gain of this pathway. cds mutants undergo light-d
ependent retinal degeneration which can be suppressed by a mutation in
phospholipase C. Thus, enzymes involved in PtdlnsP(2) metabolism regu
late phosphoinositide-mediated signalling cascades in vivo.