title: Identification and domain mapping of Dictyostelium discoideum type-1 protein phosphatase inhibitor-2.
abstract: The protein phosphatase type-1 catalytic subunit (PP1c) does not exist freely in the cell and its activity must be very strictly controlled. Several protein inhibitors of PP1c have been described including the classical mammalian inhibitor-1 (I-1) and inhibitor-2 (I-2). Association of these inhibitors with PP1c appears to involve multiple contacts and in the case of I-2 no less than five I-2 interaction subdomains have been proposed. In this report, we provide both in vitro and in vivo evidence that the Dictyostelium discoideum genome encodes a protein (DdI-2) that is an ortholog of mammalian I-2, being the first PP1c interacting protein characterized in this social amoeba. Despite the low overall sequence similarity of DdI-2 with other I-2 sequences and its long N-terminal extension, the five PP1c interaction motifs proposed for mammalian I-2 are reasonably conserved in the Dictyostelium ortholog. We demonstrate that DdI-2 interacts with and inhibits D. discoideum PP1c (DdPP1c), which we have previously characterized. Moreover, using yeast two-hybrid assays we show that a stable interaction of DdI-2 with DdPP1c requires multiple contacts.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000, São Paulo, Brazil.
authors.forename: Juliana M
authors.initials: JM
authors.lastname: Sousa-Canavez
authors.forename: Daniela
authors.initials: D
authors.lastname: Beton
authors.forename: Daniela C
authors.initials: DC
authors.lastname: Gonzalez-Kristeller
authors.forename: Aline M
authors.initials: AM
authors.lastname: da Silva
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004023:Dictyostelium / Q000737:chemistry*; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D011485:Protein Binding; D054645:Protein Phosphatase 1; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D015800:Protozoan Proteins; D020798:Two-Hybrid System Techniques; D000097847:Protein Phosphatase Inhibitory Proteins
chemical_list: D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D011506:Proteins; D015800:Protozoan Proteins; C024833:protein phosphatase inhibitor-2; D000097847:Protein Phosphatase Inhibitory Proteins