Figure 2.

Vitamin B₆ biosynthesis in higher plants. (a) Chemical structure of phosphorylated B₆ vitamers. (b) Vitamin B₆ de novo biosynthesis and salvage pathways. Both pathways are present in the cytosol. Because it is unclear whether they are also active in the chloroplasts, we did not assign a specific cellular localization for either pathway. Either RiB or RuP, as well as GAP or DAP, can be used. phosphate; RuP, ribulose 5′-phosphate; RiP, ribose 5′-phosphate; DXP, deoxyxylulose 5′-phosphate; Gln, glutamine; PL, pyridoxal; PLP, pyridoxal 5′-phosphate; PM, pyridoxamine; PMP, pyridoxamine 5′-phosphate; PN, pyridoxine; PNP, pyridoxine 5′-phosphate; PDXK, pyridoxine kinase; PDXH, pyridoxine dehydrogenase.