Interaction of neuronal calcium sensor-1 (NCS-1) with phosphatidylinositol 4-kinase beta stimulates lipid kinase activity and affects membrane trafficking in COS-7 cells.
Phosphatidylinositol 4-kinases (PI4K) catalyze the first step in the synthesis of phosphatidylinositol 4,5-bisphosphate, an important lipid regulator of several cellular functions. Here we show that the Ca(2+)-binding protein, neuronal calcium sensor-1 (NCS-1), can physically associate with the type III PI4Kbeta with functional consequences affecting the kinase. Recombinant PI4Kbeta, but not ... its glutathione S-transferase-fused form, showed enhanced PI kinase activity when incubated with recombinant NCS-1, but only if the latter was myristoylated. Similarly, in vitro translated NCS-1, but not its myristoylation-defective mutant, was found associated with recombinant- or in vitro translated PI4Kbeta in PI4Kbeta-immunoprecipitates. When expressed in COS-7 cells, PI4Kbeta and NCS-1 formed a complex that could be immunoprecipitated with antibodies against either proteins, and PI 4-kinase activity was present in anti-NCS-1 immunoprecipitates. Expressed NCS-1-YFP showed co-localization with endogenous PI4Kbeta primarily in the Golgi, but it was also present in the walls of numerous large perinuclear vesicles. Co-expression of a catalytically inactive PI4Kbeta inhibited the development of this vesicular phenotype. Transfection of PI4Kbeta and NCS-1 had no effect on basal PIP synthesis in permeabilized COS-7 cells, but it increased the wortmannin-sensitive [(32)P]phosphate incorporation into phosphatidylinositol 4-phosphate during Ca(2+)-induced phospholipase C activation. These results together indicate that NCS-1 is able to interact with PI4Kbeta also in mammalian cells and may play a role in the regulation of this enzyme in specific cellular compartments affecting vesicular trafficking.
Mesh Terms:
1-Phosphatidylinositol 4-Kinase, Animals, Biological Transport, COS Cells, Calcium Signaling, Calcium-Binding Proteins, Cattle, Cell Compartmentation, Cell Membrane, Cell Membrane Permeability, Cercopithecus aethiops, Lipoproteins, Myristic Acids, Neuronal Calcium-Sensor Proteins, Neuropeptides, Phosphatidylinositol Phosphates, Phosphatidylinositols, Protein Binding, Protein Processing, Post-Translational, Rats
1-Phosphatidylinositol 4-Kinase, Animals, Biological Transport, COS Cells, Calcium Signaling, Calcium-Binding Proteins, Cattle, Cell Compartmentation, Cell Membrane, Cell Membrane Permeability, Cercopithecus aethiops, Lipoproteins, Myristic Acids, Neuronal Calcium-Sensor Proteins, Neuropeptides, Phosphatidylinositol Phosphates, Phosphatidylinositols, Protein Binding, Protein Processing, Post-Translational, Rats
J. Biol. Chem.
Date: Oct. 26, 2001
PubMed ID: 11526106
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