Phosphatidylinositol-4-Kinase Catalytic Beta (PI4Kb)

The predicted 801-amino acid PI4K-beta protein contains an N-terminal lipid kinase unique domain, which is shared by members of both the PI 3-kinase and PI 4-kinase families, and a C-terminal catalytic domain, which defines this protein as a member of a much larger protein/lipid kinase family.PI4K-beta shares significant amino acid sequence similarity with yeast PIK1. Western blot analysis of mammalian cell lysates using an antibody against PI4K-beta detected a 110-kD protein. Northern blot analysis showed that PI4K-beta is ubiquitously expressed as an approximately 4-kb transcript, with highest expression in heart, pancreas, and skeletal muscle.Using the green fluorescent protein system, they demonstrated that PIK4CB is localized in the cytoplasm.