caa a22 4500 469080426 CHVBK 20180323132948.0 cr unu---uuuuu 170328e19920201xx s 000 0 eng 10.1007/BF00554428 doi (NATIONALLICENCE)springer-10.1007/BF00554428 Uptake and incorporation in pteridines of externally supplied GTP in normal and pigment-deficient eyes of Drosophila melanogaster [Elektronische Daten] [Ingvar Montell, Åsa Rasmuson, Bertil Rasmuson, Paul Holmgren] Some aspects of the synthesis of drosopterins in the eyes ofDrosophila melanogaster have been studied in flies with different levels ofwhite gene expression. The activity of GTP cyclohydrolase was found to differ between wild-type and yellow-eyed mutantsin vivo but notin vitro. To elucidate the uptake of substrate, we measured the removal of labeled GTP from the incubation medium by excised pupal eyes and followed the subsequent fate of this label. It was found that GTP was dephosphorylated to guanosine extracellularly before label was taken up by the eye tissue. The uptake was much lower in yellow and white eyes than in wild-type eyes, and in the latter, a considerable part of the label was present in pteridine compounds. The strain differences in the uptake of label seem to be due to different rates of intracellular utilization of guanine derivatives in pteridine synthesis. We suggest that this is caused by a hampered transport of precursor (possibly GTP) in white andzeste eyes through the membrane of red pigment granules. Plenum Publishing Corporation, 1992 white gene nationallicence Drosophila melanogaster nationallicence eye pigment synthesis nationallicence GTP cyclohydrolase activity nationallicence drosopterin synthesis nationallicence Montell Ingvar Department of Genetics, University of Umeå, S-901 87, Umeå, Sweden aut Rasmuson Åsa Department of Genetics, University of Umeå, S-901 87, Umeå, Sweden aut Rasmuson Bertil Department of Genetics, University of Umeå, S-901 87, Umeå, Sweden aut Holmgren Paul Department of Genetics, University of Umeå, S-901 87, Umeå, Sweden aut Biochemical Genetics Kluwer Academic Publishers-Plenum Publishers 30/1-2(1992-02-01), 61-75 0006-2928 30:1-2<61 1992 30 10528 https://doi.org/10.1007/BF00554428 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00554428 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Montell Ingvar Department of Genetics, University of Umeå, S-901 87, Umeå, Sweden aut NATIONALLICENCE 700 1- Rasmuson Åsa Department of Genetics, University of Umeå, S-901 87, Umeå, Sweden aut NATIONALLICENCE 700 1- Rasmuson Bertil Department of Genetics, University of Umeå, S-901 87, Umeå, Sweden aut NATIONALLICENCE 700 1- Holmgren Paul Department of Genetics, University of Umeå, S-901 87, Umeå, Sweden aut NATIONALLICENCE 773 0- Biochemical Genetics Kluwer Academic Publishers-Plenum Publishers 30/1-2(1992-02-01), 61-75 0006-2928 30:1-2<61 1992 30 10528 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer