The pantothenate kinase (PANK) family of proteins catalyzes the first step in coenzyme A (CoA) biosynthesis. Coenzyme A is an important coenzyme involved in the synthesis and oxidation of fatty acids, as well as the oxidation of pyruvate in the citric acid (Krebs) cycle. Pantothenate kinase 3 (PANK3) is a 370 amino acid member of the pantothenate kinase family that plays a role in the physiological regulation of the intracellular CoA concentration. Localized to the cytoplasm, PANK3 is regulated by feedback inhibition by CoA and its thioesters. PANK3 transfers a phosphate from ATP to pantothenate (Vitamin B5), resulting in formation of 4??-phosphopantothenate. Closely related to its family members, PANK1, PANK2 and PANK4, PANK3 is highly expressed in liver. Pantothenate kinase associated neurodegeneration (PKAN) results from mutations in the gene encoding PANK2, the only mitochondria targeted human PANK.