Enables 1-phosphatidylinositol-4-phosphate 5-kinase activity and identical protein binding activity. Involved in several processes, including 1-phosphatidyl-1D-myo-inositol 4,5-bisphosphate biosynthetic process; negative regulation of 1-phosphatidylinositol-4-phosphate 5-kinase activity; and positive regulation of autophagosome assembly. Located in several cellular components, including autophagosome; cytosol; and nucleoplasm. [provided by Alliance of Genome Resources, Apr 2022]