PNPO (pyridoxamine 5'-phosphate oxidase) is a 261 amino acid protein belonging to the pyridoxamine 5'-phosphate oxidase family. It is the rate-limiting enzyme in vitamin B6 synthesis. Vitamin B6 (Pyridoxal 5-prime-phosphate or PLP) is vital for normal cellular function, and some cancer cells have notable differences in vitamin B6 metabolism compared to their normal counterparts. Vitamin B6 is a required co-factor for enzymes involved in both homocysteine metabolism and synthesis of neurotransmitters such as catecholamine.Synonyms: Pyridoxamine-phosphate oxidase, Pyridoxine-5'-phosphate oxidase