Publication

Calcium homeostasis in fly photoreceptor cells

Oberwinkler, J., 2002, PHOTORECEPTORS AND CALCIUM. NEW YORK: Kluwer Academic/Plenum Publishers, p. 539-583 45 p. (ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY; vol. 514).

Research output: Chapter in Book/Report/Conference proceedingChapterAcademic

  • J Oberwinkler

In fly photoreceptor cells, two processes dominate the Ca2+ homeostasis: light-induced Ca2+ influx through members of the TRP family of ion channels, and Ca2+ extrusion by Na+/Ca2+ exchange.Ca2+ release from intracellular stores is quantitatively insignificant. Both, the light-activated channels and the Ca2+-extruding exchangers are located in or close to the rhabdomeric microvilli, small protrusions of the plasma membrane. The microvilli also contain the molecular machinery necessary for generating quantum bumps, short electrical responses caused by the absorption of a single photon. Due to this anatomical arrangement, the light-induced Ca2+ influx results in two separate Ca2+ signals that have different functions: a global, homogeneous increase of the Ca2+ concentration in the cell body, and rapid but large amplitude Ca2+ transients in the microvilli. The global rise of the Ca2+ concentration mediates light adaptation, via regulatory actions on the phototransduction cascade, the voltage-gated K+ channels and small pigment granules controlling the light intensity. The local Ca2+ transients in the microvilli are responsible for shaping the quantum bumps into fast, all-or-nothing events. They achieve this by facilitating strongly the phototransduction cascade at early stages of the light response and subsequently inhibiting it. Many molecular targets of these feedback mechanisms have been identified and characterized due to the availability of numerous Drosophila mutant showing defects in the phototransduction.

Original languageEnglish
Title of host publicationPHOTORECEPTORS AND CALCIUM
Place of PublicationNEW YORK
PublisherKluwer Academic/Plenum Publishers
Pages539-583
Number of pages45
Publication statusPublished - 2002

Publication series

NameADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY
PublisherKLUWER ACADEMIC/PLENUM PUBL
Volume514
ISSN (Print)0065-2598

    Keywords

  • LIGHT-SENSITIVE CHANNELS, PROTEIN-KINASE-C, HONEY-BEE DRONE, LIMULUS VENTRAL PHOTORECEPTORS, PDZ-DOMAIN PROTEIN, OMMOCHROME PIGMENT GRANULES, DROSOPHILA-NINAC KINASE, CAPACITATIVE CA2+ ENTRY, ADAPTING-BUMP MODEL, RHODOPSIN IN-VIVO

ID: 4107690