Abstract
Rac, a member of the Rho family of monomeric GTPases, is an integrator of intracellular signaling in a wide range of cellular processes. We have purified a PtdIns(3,4,5)P3-sensitive activator of Rac from neutrophil cytosol. It is an abundant, 185 kDa guanine-nucleotide exchange factor (GEF), which we cloned and named P-Rex1. The recombinant enzyme has Rac-GEF activity that is directly, substantially, and synergistically activated by PtdIns(3,4,5)P3 and Gbetagammas both in vitro and in vivo. P-Rex1 antisense oligonucleotides reduced endogenous P-Rex1 expression and C5a-stimulated reactive oxygen species formation in a neutrophil-like cell line. P-Rex1 appears to be a coincidence detector in PtdIns(3,4,5)P3 and Gbetagamma signaling pathways that is particularly adapted to function downstream of heterotrimeric G proteins in neutrophils.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Cell Fractionation
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Cell Line
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Cloning, Molecular
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Cytosol / metabolism
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Guanine Nucleotide Exchange Factors / genetics*
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Guanine Nucleotide Exchange Factors / metabolism*
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Heterotrimeric GTP-Binding Proteins / metabolism
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Humans
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In Vitro Techniques
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Molecular Sequence Data
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Neutrophils / cytology
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Neutrophils / metabolism
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Phenotype
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Phosphatidylinositol Phosphates / metabolism*
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Phosphoric Monoester Hydrolases / metabolism
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Platelet-Derived Growth Factor / pharmacology
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Reactive Oxygen Species / metabolism
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Signal Transduction / drug effects
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Signal Transduction / physiology
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Swine
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rac GTP-Binding Proteins / metabolism*
Substances
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Guanine Nucleotide Exchange Factors
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PREX1 protein, human
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Phosphatidylinositol Phosphates
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Platelet-Derived Growth Factor
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Reactive Oxygen Species
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phosphatidylinositol 3,4,5-triphosphate
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Phosphoric Monoester Hydrolases
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phosphatidylinositol-3,4-bisphosphate 4-phosphatase
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Heterotrimeric GTP-Binding Proteins
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rac GTP-Binding Proteins