Regulation of GRP1-catalyzed ADP Ribosylation Factor Guanine Nucleotide Exchange by Phosphatidylinositol 3,4,5-Trisphosphate

• DOI: 10.1074/jbc.273.4.1859
• Publication Date: 2002-07-26T14:56:15Z
• Authors: Jes K. Klarlund; Lucia E. Rameh; Lewis C. Cantley; Joanne M. Buxton; John J. Holik; Christoper Sakelis; Varsha Patki; Silvia Corvera; Michael P. Czech
• Keywords: Pleckstrin homology domain; ADP ribosylation factor

Cellular levels of phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P₃) are rapidly elevated in response to activation growth factor receptor tyrosine kinases. This polyphosphoinositide binds the pleckstrin homology (PH) domain GRP1, a protein that also contains 200 residues with high sequence similarity segment yeast Sec7 functions as an ADP ribosylation exchange (ARF) (Klarlund, J., Guilherme, A., Holik, J. Virbasius, V., Chawla, and Czech, M. P. (1997)<i>Science</i> 275, 1927–1930). Here we show dioctanoyl PtdIns(3,4,5)P₃ PH GRP1 a<i>K</i> _d = 0.5 μm, affinity 2 orders magnitude greater than dioctanoyl-PtdIns(4,5)P₂. Further, is found catalyze guanine nucleotide ARF1 -5 but not ARF6. Importantly, PtdIns(3,4,5)P₃, PtdIns(4,5)P₂, markedly enhances ARF activity reaction mixture containing dimyristoylphosphatidylcholine micelles, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid, low concentration sodium cholate. PtdIns(3,4,5)P₃-mediated through selectively blocked by 100 μm inositol 1,3,4,5-tetrakisphosphate, which GRP1. Taken together, these data consistent hypothesis selective recruitment membranes activates -5, known regulators intracellular membrane trafficking.