title: Identification of an animal sucrose transporter.
abstract: According to a classic tenet, sugar transport across animal membranes is restricted to monosaccharides. Here, we present the first report of an animal sucrose transporter, SCRT, which we detected in Drosophila melanogaster at each developmental stage. We localized the protein in apical membranes of the late embryonic hindgut as well as in vesicular membranes of ovarian follicle cells. The fact that knockdown of SCRT expression results in significantly increased lethality demonstrates an essential function for the protein. Experiments with Saccharomyces cerevisiae as a heterologous expression system revealed that sucrose is a transported substrate. Because the knockout of SLC45A2, a highly similar protein belonging to the mammalian solute carrier family 45 (SLC45) causes oculocutaneous albinism and because the vesicular structures in which SCRT is located appear to contain melanin, we propose that these organelles are melanosome-like structures and that the transporter is necessary for balancing the osmotic equilibrium during the polymerization process of melanin by the import of a compatible osmolyte. In the hindgut epithelial cells, sucrose might also serve as a compatible osmolyte, but we cannot exclude the possibility that transport of this disaccharide also serves nutritional adequacy.
authors.affiliation: Department of Biology and Chemistry, University of Osnabrück, 49069 Osnabrück, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Meyer
authors.forename: Olga
authors.initials: O
authors.lastname: Vitavska
authors.forename: Helmut
authors.initials: H
authors.lastname: Wieczorek
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001692:Biological Transport; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D026901:Membrane Transport Proteins; D013395:Sucrose