Drosophila melanogaster protein phosphatase inhibitor-2: identification of a site important for PP1 inhibition.
A database search with human protein phosphatase inhibitor-2 (I-2) identified a Drosophila melanogaster cDNA that encoded a protein identical in length and sharing 39% amino acid identity (58% similarity) with human I-2. The mRNA encoding this protein is expressed in both sexes and throughout development, unlike Drosophila inhibitor-t. The bacterially expressed protein was a specific inhibitor of protein phosphatase 1 with an IC(50) of <1 nM, confirming that it is the Drosophila homologue of mammalian inhibitor-2. Mutation of Phe residues conserved in I-2 from lower and higher eukaryotes showed that Phe-33 is important for inhibition of PP1c.
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Medical Research Council Protein Phosphorylation Unit, Department of Biochemistry, MSI/WTB Complex, University of Dundee, Dundee, UK. n.r.helps@dundee.ac.uk
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D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004331:Drosophila melanogaster / Q000201:enzymology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D011487:Protein Conformation; D054645:Protein Phosphatase 1; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D000097847:Protein Phosphatase Inhibitory Proteins
D018076:DNA, Complementary; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D011506:Proteins; C024833:protein phosphatase inhibitor-2; D000097847:Protein Phosphatase Inhibitory Proteins