▪ Abstract The Drosophila phototransduction cascade has emerged as an attractive
paradigm for understanding the molecular mechanisms underlying visual transduction, as
well as other G protein–coupled signaling cascades that are activated and terminated with
great rapidity. A large collection of mutants affecting the fly visual cascade have been
isolated, and the nature and function of many of the affected gene products have been
identified. Virtually all of the proteins, including those that were initially classified as novel …