title: Functional regulation of glutamine:fructose-6-phosphate aminotransferase 1 (GFAT1) of Drosophila melanogaster in a UDP-N-acetylglucosamine and cAMP-dependent manner.
abstract: Glutamine:fructose-6-phosphate aminotransferase (GFAT; EC 2.6.1.16) expression is tightly regulated in the context of amino sugar synthesis in many organisms from yeast to humans by transcriptional and post-translational processes. We have cloned the cDNA of the GFAT1 of Drosophila melanogaster (Dmel/Gfat1). One of the two putative protein kinase A (PKA) phosphorylation sites proposed for the regulation of human GFAT1 [Zhou, Huynh, Hoffmann, Crook, Daniels, Gulve and McClain (1998) Diabetes 47, 1836-1840] is conserved in Dmel/GFAT1. In the other one the reactive serine has been converted to a cysteine, making further access by PKA unlikely. The Dmel/Gfat1 gene is localized at position 81F on the right arm of chromosome 3. By whole-mount in situ hybridization specific expression of Dmel/GFAT1 was detected in embryonic chitin-synthesizing tissues and in the corpus cells of salivary glands from late third larval instar. Expressing Dmel/GFAT1 in yeast we showed that Dmel/GFAT1 activity is controlled by UDP-N-acetylglucosamine and PKA in the yeast total protein extract system. We propose a model for the independent regulation of the Dmel/GFAT1 enzyme by feedback inhibition and PKA.
authors.affiliation: Institute for Biology-Genetics, Free University of Berlin, Arnimallee 7, D-14195 Berlin, Germany. graack@meditarget.de
authors.forename: H R
authors.initials: HR
authors.lastname: Graack
authors.forename: U
authors.initials: U
authors.lastname: Cinque
authors.forename: H
authors.initials: H
authors.lastname: Kress
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D018076:DNA, Complementary / Q000032:analysis / Q000302:isolation & purification; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D017344:Genes, Insect; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing) / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000502:physiology*
chemical_list: D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D014157:Transcription Factors; D014537:Uridine Diphosphate N-Acetylglucosamine; D000242:Cyclic AMP; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing); D017868:Cyclic AMP-Dependent Protein Kinases