Cytosolic pantothenate kinases 1 and 3 (PANK1, PANK3) catalyze the reaction of ATP and pantothenate to form ADP and phosphopantothenate. This enzymatic activity has been demonstrated in crude cell extracts for two isoforms of mouse pantothenate kinase 1 (Rock et al. 2002) and for their human homologues (Ramaswamy and 2004). An additional human gene, PANK3, encodes a closely related protein but pantothenate kinase activity has not been demonstrated experimentally for it (Cavestro et al. 2023; Leonardi et al. 2005; Zhou et al. 2001).