Phosphorylates (R)-pantoate to form (R)-4-phosphopantoate in the CoA biosynthesis pathway (PubMed:23200110). ATP is the best phosphate donor. Can be replaced with UTP, with lower efficiency (PubMed:23200110). (R)-pantoate + ATP = (R)-4-phosphopantoate + ADP + H(+) Optimum pH is 8.5. Optimum temperature is 40 degrees Celsius. Cofactor biosynthesis; coenzyme A biosynthesis. Belongs to the GHMP kinase family. PoK subfamily.