title: Calcium-activated potassium channel gene expression in the midgut of Drosophila.
abstract: The slowpoke gene of Drosophila encodes a pore-forming subunit of a BK-type Ca(2+)-activated K+ channel. The gene is expressed in neurons, muscles, tracheal cells and in the midgut. The P1 transgene gene contains the entire slowpoke transcriptional control region and drives the expression of a reporter protein comprised of slowpoke amino terminal sequences fused to beta-galactosidase. Here we show that midgut expression is limited to the copper cell and iron cell regions. The copper cell region is composed of two cell types, the copper cells and the interstitial cells. The P1 transgene is expressed in the interstitial cells but not the copper cells. Furthermore, we show that the reporter protein is apically localized in the interstitial cells. In these cells, the slowpoke Ca(2+)-activated K+ channel is thought to participate in the transport of ions between the hemolymph and the lumen of the gut. Subcellularly localized BK channels may be involved in the secretion of acid into the gut lumen. An analogous role for basolaterally localized BK channels has been proposed in the acid-secreting intercalating cells of the human kidney.
authors.affiliation: Department of Zoology, University of Texas at Austin 78712-1064, USA.
authors.forename: R
authors.initials: R
authors.lastname: Brenner
authors.forename: N S
authors.initials: NS
authors.lastname: Atkinson
mesh_terms: D000818:Animals; D003300:Copper / Q000378:metabolism; D004330:Drosophila / Q000235:genetics* / Q000254:growth & development; D029721:Drosophila Proteins; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology*; D007501:Iron / Q000378:metabolism; D051036:Large-Conductance Calcium-Activated Potassium Channels; D007814:Larva; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions; D019076:Transgenes; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D011993:Recombinant Fusion Proteins; C059843:lab protein, Drosophila; C494844:slo protein, Drosophila; D003300:Copper; D007501:Iron; D001616:beta-Galactosidase