Mutations in calphotin, the gene encoding a Drosophila photoreceptor cell-specific calcium-binding protein, reveal roles in cellular morphogenesis and survival.
Calphotin is a Drosophila photoreceptor cell-specific protein expressed very early in eye development, at the time when cell-type decisions are being made. Calphotin is a very hydrophobic and proline-rich protein which lacks obvious transmembrane domains. The cDNA encoding Calphotin was mapped to a region removed by a set of existing chromosomal deletions. Mutations that alter photoreceptor cell structure and development were isolated that fail to complement these deletions. These mutations fall into two classes. Class I mutations alter the structure of the rhabdomere, a photoreceptor cell organelle specialized for phototransduction. Class II mutations have rough eyes, due to misorientation of the rhabdomeres and photoreceptor cell death. Transformation rescue of these phenotypes in transgenic flies bearing calphotin genomic DNA indicates that both classes of mutations are in the calphotin gene. Analysis of these mutations suggest that Calphotin plays important roles in both rhabdomere development and in photoreceptor cell survival.
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Graduate Program in Molecular Biology, Cornell University Graduate School of Medical Sciences, New York, New York 10021.
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D000818:Animals; D030801:Animals, Genetically Modified; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002470:Cell Survival; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D029721:Drosophila Proteins; D005720:Gamma Rays; D017344:Genes, Insect / Q000528:radiation effects; D005804:Genes, Lethal; D005816:Genetic Complementation Test; D007301:Insect Hormones / Q000235:genetics*; D019476:Insect Proteins; D016350:Leucine Zippers; D008854:Microscopy, Electron; D009024:Morphogenesis; D009030:Mosaicism; D016296:Mutagenesis; D015388:Organelles / Q000502:physiology / Q000648:ultrastructure; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D015183:Restriction Mapping
D002135:Calcium-Binding Proteins; C079658:Cpn protein, Drosophila; D029721:Drosophila Proteins; D007301:Insect Hormones; D019476:Insect Proteins