- Converted to pyridoxal phosphate (PLP), a cofactor used in transamination (eg, ALT and AST), decarboxylation reactions, glycogen phosphorylase.- Synthesis of cystathionine, heme, niacin, histamine, and neurotransmitters including serotonin, epinephrine, norepinephrine, dopamine, and GABA.

Deficiency:- Convulsions, hyperirritability, peripheral neuropathy (deficieny inducible by isoniazid and oral contraceptives)- Sideroblastic anemias (due to impaired hemoglobin synthesis and iron excess).