Isolation of a putative phospholipase C gene of Drosophila, norpA, and its role in phototransduction
Abstract
Severe norpA mutations in Drosophila eliminate the photoreceptor potential, cause age-dependent photoreceptor degeneration, and render the fly completely blind. Recent biochemical analyses have shown that norpA mutants lack phospholipase C (PLC) activity in the eye. In a wide range of cells involving diverse stimuli, inositol lipid-hydrolyzing PLCs appear to couple the activation of many receptors with their ultimate cellular effects. Although previous work has suggested that this is the case for the light-evoked response of the invertebrate photoreceptor, the evidence has not been conclusive. A combination of chromosomal walking and transposon-mediated mutagenesis was used to clone the norpA gene. This gene encodes a 7.5 kb RNA that is expressed in the adult head. In situ hybridizations of norpA cDNA to adult tissue sections show that the gene is expressed abundantly in the retina. The putative norpA protein is composed of 1095 amino-acid residues and has extensive sequence similarity to three classes of PLC found in bovine and rat brain. This evidence suggests that the norpA gene encodes a PLC expressed in the eye of Drosophila and that PLC is an essential component of the Drosophila phototransduction pathway. .
Degree
Ph.D.
Advisors
Pak, Purdue University.
Subject Area
Biology|Genetics
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