title: Functional characterization of ecto-5'-nucleotidases and apyrases in Drosophila melanogaster.
abstract: Ecto-5'-nucleotidases are glycosyl phosphatidylinositol (GPI)-linked membrane-bound glycoproteins that convert extracellular AMP to adenosine. They play important roles in the inflammatory response where they modulate levels of pro-inflammatory extracellular ATP and anti-inflammatory extracellular adenosine. They are found in the saliva of blood feeding insects and also have a role in male reproduction. Drosophila possesses five genes with eight alternative transcripts encoding proteins with sequence homology to mammalian ecto-5'-nucleotidases. Here we show that two of them - NT5E-1 (CG4827) and NT5E-2 (CG30104) - are GPI-linked proteins with ecto-5'-nucleotidase activity but that they can also be released from the GPI anchor and exhibit secreted 5'-nucleotidase activity in growth media. The third locus in the cluster, CG30103, most likely also encodes a GPI-anchored membrane-bound protein but without 5'-nucleotidase activity, possibly due to the numerous substitutions in the amino acid sequence. Together with NT5E-2, CG30103 is also expressed in the testis offering an interesting model to investigate ecto-5'-nucleotidase enzymatic and extra-enzymatic function in male reproduction. CG42249 locus encoding two alternative transcripts is sequentially similar to family of apyrases related to 5'-nucleotidases and we show here that together with CG5276 belonging to another family of calcium-activated nucleotidases function as apyrases converting extracellular ATP to ADP and AMP. The last locus, CG11883, encodes most likely a cytoplasmic/mitochondrial protein.
authors: University of South Bohemia, Ceske Budejovice 37005, Czech Republic.
authors: Michaela
authors: M
authors: Fenckova
authors: Radka
authors: R
authors: Hobizalova
authors: Zdenek Faltynek
authors: ZF
authors: Fric
authors: Tomas
authors: T
authors: Dolezal
mesh_terms: D015720:5'-Nucleotidase / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001081:Apyrase / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D005810:Multigene Family
chemical_list: D029721:Drosophila Proteins; D015720:5'-Nucleotidase; D001081:Apyrase