The conjugation of cysteine (Cys) and 4'- phosphopantothenate (PPanK) to form 4-phosphopantothenoylcysteine (PPC) , coupled to the conversion of ATP to AMP and pyrophosphate, is catalyzed by cytosolic phosphopantothenate-cysteine ligase (PPCS aka Phosphopantothenoylcysteine synthase or PPC synthase). Mammalian PPCS prefers ATP to CTP, unlike the E. coli ortholog (Daughtery et al. 2002; Manoj et al. 2003).
de Crecy-Lagard, V,
phosphopantothenate--cysteine ligase activity of 2xPPCS [cytosol]