PI5P4Kβ

PI5P4Kβ (phosphatidylinositol-5-phosphate 4-kinase beta) is a lipid kinase that phosphorylates phosphatidylinositol 5-phosphate^[PI(5)P] and functions as an intracellular GTP sensor, linking phosphoinositide metabolism to cellular metabolic status^[1]. Mechanistically, PI5P4Kβ preferentially utilizes GTP rather than ATP as a phosphate donor, and its kinase activity reflects changes in intracellular GTP availability, providing a direct connection between nucleotide metabolism and phosphoinositide signaling^[1]. This GTP-responsive property supports regulation of metabolism, stress responses, and tumorigenesis-associated processes, making PI5P4Kβ a unique signaling node in cellular adaptation pathways^[1]. In disease-relevant experimental models, PI5P4Kβ-dependent GTP sensing has been associated with metabolic regulation and tumorigenesis, highlighting its value as a target for mechanistic studies of cancer cell fitness and nutrient-responsive signaling^[1]. Compared with related phosphoinositide kinases that primarily function as ATP-dependent enzymes, PI5P4Kβ possesses an unusual nucleotide preference that evolved through a guanine-recognition mechanism and enables selective sensing of GTP pools^[2][3]. Structural and biochemical analyses identified a short nucleotide-recognition motif that mediates GTP preference and underlies the molecular evolution of this kinase from an ATP-utilizing ancestor^[2][3]. For experimental applications, the development of selective PI5P4K inhibitors has provided chemical tools for dissecting PI5P4K signaling networks and evaluating the biological consequences of PI5P4Kβ modulation in cellular systems^[4].