Phosphatidylinositol-4-Kinase Type 2 Beta (PI4K2b)

PI4K2B is a primarily cytosolic PI4K that is recruited to membranes, where it stimulates phosphatidylinositol 4,5-bisphosphate synthesis.The deduced 490-amino acid PI4K2B protein has a calculated molecular mass of 54 kD and differs from PI42KA primarily in the N terminus. Northern blot analysis showed ubiquitous expression of a 3.8-kb primary PI4K2B transcript. Relative to PI4K2A, expression of PI4K2B was higher in liver, but lower in brain and peripheral blood leukocytes. Confocal microscopy revealed expression of PI4K2B in intracellular membranes, particularly in early endosomes, as indicated by colocalization with EEA1. PI4K2B showed little or no colocalization with Golgi bodies, and its N-terminal region was required for membrane localization.