UDP-N-acetylglucosamine pyrophosphorylase; Catalyzes the last two sequential reactions in the de novo biosynthetic pathway for UDP-GlcNAc. Responsible for the acetylation of Glc-N-1-P to give GlcNAc-1-P and for the uridyl transfer from UTP to GlcNAc-1-P which produces UDP-GlcNAc (By similarity) (458 aa)