sentences:  Orotidylate decarboxylase is located at the C-terminal domain of UMPS and converts this orotidylate intermediate into uridine monophosphate (also referred to as uridylate or UMP) via decarboxylation.These two-steps are rapid and irreversible in mammals.In other pyrimidine auxotrophs that do not have this bifunctional enzyme, usually less complex organisms, two separate enzymes are required to carry out this reaction.