The pantothenate kinase (PANK) family of proteins catalyzes the first step in coenzyme A (CoA). Pantothenate kinase 1 (PANK1) is a 598 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, PANK1 is strongly inhibited by acetyl-CoA and manyl-CoA, as well as by high concentration of non-esterified CoA (CoASH). Four known isoforms of PANK1 exist as a result of alternative splicing events. Of these isoforms, PANK1a and PANK1b have been identified as the catalytically active isoforms. Isoform PANK1a is most highly expressed in brain, heart, kidney, liver, skeletal muscle and kidney. Isoform PANK1b is detected at much lower levels in kidney, liver, brain and testis and is not detected in heart or skeletal muscle.