Stimulation of UDP-N acetyl glucosamine: Glycoprotein N-acetyl glucosaminyl transferase activity by cytidine 5′-diphospho-choline

Abstract

Golgi-rich and golgi-depleted heterogenous membrane fractions were prepared from livers of rats fed choline supplemented or deficient diets. Assay of UDP-N-acetyl glucosamine: glycoprotein N-acetyl glucosaminyl transferase activity showed a decrease of the enzyme activity in the golgi-depleted membrane fraction of the choline deficient liver. A marked stimulation of the enzyme activity in the same fraction was observed by in vitro additions of phosphorylcholine plus cytidine 5′-triphosphate or cytidine 5′-diphospho-choline. This stimulation was found to be dose dependent. Two possible mechanisms are suggested for the observed effect.