Participates in the biosynthesis of phosphatidylinositol 4,5-bisphosphate. Preferentially utilizes GTP, rather than ATP, for PI(5)P phosphorylation and its activity reflects changes in direct proportion to the physiological GTP concentration. Its GTP-sensing activity is critical for metabolic adaptation. In collaboration with PIP4K2A, has a role in mediating autophagy in times of nutrient stress (PubMed:29727621). Required for autophagosome-lysosome fusion and the regulation of cellular lipid metabolism (PubMed:29727621). PIP4Ks negatively regulate insulin signaling through a catalytic-independent mechanism. They interact with PIP5Ks and suppress PIP5K-mediated PtdIns(4,5)P2 synthesis and insulin-dependent conversion to PtdIns(3,4,5)P3 (By similarity). a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-5-phosphate) + ATP = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-4,5-bisphosphate) + ADP + H(+) 1,2-dihexadecanoyl-sn-glycero-3-phospho-(1D-myo-inositol-5-phosphate) + ATP = 1,2-dihexadecanoyl-sn-glycero-3-phospho-(1D-myo-inositol-4,5-bisphosphate) + ADP + H(+) 1,2-dihexadecanoyl-sn-glycero-3-phospho-(1D-myo-inositol-5-phosphate) + GTP = 1,2-dihexadecanoyl-sn-glycero-3-phospho-(1D-myo-inositol-4,5-bisphosphate) + GDP + H(+) Homodimer. Binds TNFRSF1A. Interacts with PIP4K2A; the interaction suppresses ubiquitination by the SPOP/CUL3 complex (By similarity). Probably interacts with PIP5K1A; the interaction inhibits PIP5K1A kinase activity (By similarity). Associated with the plasma membrane and the endoplasmic reticulum. Ubiquitinated by the SPOP/CUL3 complex. Ubiquitination is stimulated by PtdIns5P levels. Phosphorylated on serine residues.