title: Homo sapiens dullard protein phosphatase shows a preference for the insulin-dependent phosphorylation site of lipin1.
abstract: Human lipin1 catalyzes the highly regulated conversion of phosphatidic acids to diacylglycerides. Lipin's cellular location, protein partners, and biological function are directed by phosphorylation-dephosphorylation events catalyzed by the phosphoserine phosphatase dullard. To define the determinants of dullard substrate recognition and catalysis, and hence, lipin regulation, steady-state kinetic analysis was performed on phosphoserine-bearing nonapeptides based on the phosphorylation sites of lipin. The results demonstrate that dullard shows specificity for the peptide corresponding to the insulin-dependent phosphorylation site (Ser106) of lipin with a k(cat)/K(m) of 2.9 × 10(4) M(-1) s(-1). These results are consistent with a coil-loop structure for the insulin-dependent phosphorylation site on human lipin1 and make unlikely the requirement for an adaptor protein to confer activity such as that proposed for the yeast homologue.
authors.affiliation: Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
authors.forename: Rui
authors.initials: R
authors.lastname: Wu
authors.forename: Megan
authors.initials: M
authors.lastname: Garland
authors.forename: Debra
authors.initials: D
authors.lastname: Dunaway-Mariano
authors.forename: Karen N
authors.initials: KN
authors.lastname: Allen
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D010711:Phosphatidate Phosphatase; D010749:Phosphoprotein Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D013379:Substrate Specificity
chemical_list: D007328:Insulin; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C499225:CTDNEP1 protein, human; D010749:Phosphoprotein Phosphatases; D010744:Phosphoric Monoester Hydrolases; C485999:LPIN1 protein, human; D010711:Phosphatidate Phosphatase