Uridine diphosphate

Uridine diphosphate, abbreviated UDP, is an organic compound. It is an ester of pyrophosphoric acid with the nucleosideuridine. UDP consists of the pyrophosphategroup, the pentosesugarribose, and the nucleobaseuracil.

UDP is an important factor in glycogenesis. Before glucose can be stored as glycogen in the liver and muscles, the enzymeUDP-glucose pyrophosphorylase forms a UDP-glucose unit by combining glucose 1-phosphate with uridine triphosphate, cleaving a pyrophosphate ion in the process. Then, the enzyme glycogen synthase combines UDP-glucose units to form a glycogen chain. The UDP molecule is cleaved from the glucose ring during this process and can be reused by UDP-glucose pyrophosphorylase.