Phosphatidylinositol 4,5-bisphosphate phosphatase regulates the rearrangement of actin filaments.

摘要: Phosphatidylinositol 4,5-bisphosphate (PIP2) reorganizes actin filaments by modulating the functions of a variety actin-regulatory proteins. Until now, it was thought that bound PIP2 is hydrolyzed only tyrosine-phosphorylated phospholipase Cgamma (PLCgamma) after activation tyrosine kinases. Here, we show new mechanism for hydrolysis and regulation phosphatase (synaptojanin). We isolated 150-kDa protein (p150) from brains binds SH3 domains Ash/Grb2. The sequence this found to be homologous synaptojanin. expression p150 in COS 7 cells produces decrease number stress fibers center causes become multinuclear. On other hand, phosphatase-negative mutant does not disrupt or produce multinuclear phenotype. have also shown forms complexes with Ash/Grb2 epidermal growth factor (EGF) receptors when are treated EGF an EGF-dependent manner. Moreover, activity native purified bovine inhibited profilin, cofilin, alpha-actinin, although PLCdelta1 markedly these Furthermore, suppresses gelation, which induced smooth muscle alpha-actinin. All data suggest (synaptojanin) hydrolyzes regulatory proteins, resulting rearrangement downstream kinase