Glucose-1-phosphate uridylyl transferase activity in developing rat liver.

Glucose-i-phosphate (G-1-P) uridylyl transferase, E.C. 2.7.7.9,' catalyzes the reversible synthesis of uridinediphosphoglucose (UDPG) from G-1-P and uridine triphosphate with the liberation of pyrophosphate. This reaction appears to be ubiquitous in nature.! The importance of this enzyme is evident from its participation in the metabolic pathways of glycogen synthesis,' galactose conversion to glucose,' detoxication of certain compounds by glucuronosylation" and synthesis of mucopolysaccharides,7 among others. In rat liver homogenate the enzyme is present in the soluble fraction exclusively."9 Previously published data on the activity of this enzyme in rat liver at various ages have differed widely and have not been comprehensive (Table 1). The present studies demonstrate a striking developmental pattern for this enzyme.