GDE1/MIR16 Is a Glycerophosphoinositol Phosphodiesterase Regulated by Stimulation of G Protein-Coupled Receptors

• Published in: Proceedings of the National Academy of Sciences - PNAS 2003-02, Vol.100 (4), p.1745-1750
• Main Authors: Zheng, Bin, Berrie, Christopher P., Corda, Daniela, Farquhar, Marilyn G.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Animals; Biological Sciences; Catalytic Domain; Cell Line; Cell membranes; Chromatography, High Pressure Liquid; GTP-Binding Proteins - metabolism; Humans; Hydrolysis; Mice; Molecular Sequence Data; Mutagenesis, Site-Directed; Neurotransmitters; P branes; Phosphatidylinositols; Phosphoric Diester Hydrolases - chemistry; Phosphoric Diester Hydrolases - genetics; Phosphoric Diester Hydrolases - physiology; Physiological regulation; Protein metabolism; Proteins; Receptors; Receptors, Cell Surface - physiology; RGS proteins; Sequence Homology, Amino Acid; Substrate Specificity
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0337605100

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, α/β-adrenergic, and lysophospholipid receptors. Membrane topology studies suggest a model in which the catalytic GDE domain faces the lumen/extracellular 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.