Vitamin B6 transporter

The Vitamin B6 transporter facilitates the uptake and intracellular distribution of vitamin B6 vitamers, including non-phosphorylated forms like pyridoxine (PN), pyridoxal (PL), and pyridoxamine (PM), as well as the active phosphorylated form pyridoxal 5'-phosphate (PLP), across plasma membranes and into subcellular compartments such as mitochondria. In mammals, tissues transport these non-phosphorylated vitamers from plasma after dephosphorylation of circulating PLP by alkaline phosphatases, enabling conversion to PLP inside cells for use as a coenzyme in over 100 enzymes involved in amino acid metabolism, heme biosynthesis, and glycogen breakdown. Specific carriers like the mitochondrial transporter Mtm1p in yeast (homologous roles likely in humans) import PLP into mitochondria, linking B6 transport to iron homeostasis and Fe-S cluster assembly. In plants and yeast, plasma membrane transporters from the purine permease (PUP) family or Tpn1p/Bsu1 handle extracellular import of non-phosphorylated B6, while dynamic membrane pores formed by NAPE-PLD may aid diffusion of charged PLP across organelle membranes in the presence of bile acids. Dysregulation of B6 transport contributes to altered vitamer levels in diseases like cancer, where Wnt signaling modulates related enzymes like PDXK, potentially shifting B6 to inactive forms and affecting tumor growth. No drugs directly target these transporters, but their role is critical for preventing B6 deficiency-related metabolic disruptions.

Other names

Vitamin B6 membrane transporterB6 vitamer transporterPLP transporter (for phosphorylated forms)PN/PL/PM transporter (for non-phosphorylated forms)