title: GDE1/MIR16 is a glycerophosphoinositol phosphodiesterase regulated by stimulation of G protein-coupled receptors.
abstract: Previously we identified MIR16 (membrane interacting protein of RGS16) as an integral membrane glycoprotein that interacts with regulator of G protein signaling proteins and shares significant sequence homology with bacterial glycerophosphodiester phosphodiesterases (GDEs), suggesting that it is a putative mammalian GDE. Here we show that MIR16 belongs to a large, evolutionarily conserved family of GDEs with a characteristic putative catalytic domain that shares a common motif (amino acids 92-116) with the catalytic domains of mammalian phosphoinositide phospholipases C. Expression of wild-type MIR16 (renamed GDE1), but not two catalytic domain mutants (E97A/D99A and H112A), leads to a dramatic increase in glycerophosphoinositol phosphodiesterase (GPI-PDE) activity in HEK 293T cells. Analysis of substrate specificity shows that GDE1/MIR16 selectively hydrolyzes GPI over glycerophosphocholine. The GPI-PDE activity of GDE1/MIR16 expressed in HEK 293T cells can be regulated by stimulation of G protein-coupled, alpha/beta-adrenergic, and lysophospholipid receptors. Membrane topology studies suggest a model in which the catalytic GDE domain faces the lumenextracellular space and the C terminus faces the cytoplasm. Our results suggest that by serving as a PDE for GPI with its activity regulated by G protein signaling, GDE1/MIR16 provides a link between phosphoinositide metabolism and G protein signal transduction.
authors.affiliation: Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0651, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Berrie
authors.forename: Daniela
authors.initials: D
authors.lastname: Corda
authors.forename: Marilyn G
authors.initials: MG
authors.lastname: Farquhar
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D011956:Receptors, Cell Surface; D010727:Phosphoric Diester Hydrolases; C021491:glycerophosphoinositol glycerophosphodiesterase; D019204:GTP-Binding Proteins