The function of COASY (Coenzyme A synthase, Ensembl gene identifier ENSG00000068120) is as follows. Bifunctional enzyme that catalyzes the fourth step of the coenzyme A biosynthetic pathway, the adenylation of 4'- phosphopantetheine, and the fifth step, the phosphorylation of dephospho-CoA to CoA. {ECO:0000269|PubMed:11923312, ECO:0000269|PubMed:24360804}.