Stt4 PI 4-kinase localizes to the plasma membrane and functions in the Pkc1-mediated MAP kinase cascade.

Production of the essential phospholipid PI4P at the Golgi by the Pik1 kinase is required for protein secretion, while a distinct pool of PI4P generated by the Stt4 kinase is critical for normal actin cytoskeleton organization. We identify a transmembrane protein that stabilizes Stt4 at the plasma membrane where it ...
directs synthesis of PI4P, which is required for activation of the Rho1/Pkc1-mediated MAP kinase cascade. Inactivation of Stt4 or the PI4P 5-kinase Mss4 results in mislocalization of the Rho-GTPase GEF Rom2. Rom2 binds PI4,5P(2) through its PH domain and represents the first identified effector in the Stt4-Mss4 pathway. Based on these results, we propose that Stt4-Mss4 generates PI4,5P(2) at the plasma membrane, required to recruit/activate effector proteins such as Rom2.
Mesh Terms:
1-Phosphatidylinositol 4-Kinase, Cell Membrane, Enzyme Activation, Fungal Proteins, Genes, Fungal, Genes, Suppressor, Mitogen-Activated Protein Kinases, Models, Biological, Phosphatidylinositol Phosphates, Phosphotransferases, Phosphotransferases (Alcohol Group Acceptor), Protein Kinase C, Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Dev. Cell
Date: May. 01, 2002
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