UDP-N-acetylglucosamine pyrophosphorylase that utilizes N-acetylglucosamine-1-phosphate as substrate (PubMed:9603950). Together with AGM1, is involved in the production of UDP-N-acetylglucosamine from N-acetylglucosamine-6-phosphate (PubMed:9603950). H(+) + N-acetyl-alpha-D-glucosamine 1-phosphate + UTP = diphosphate + UDP-N-acetyl-alpha-D-glucosamine Nucleotide-sugar biosynthesis; UDP-N-acetyl-alpha-D-glucosamine biosynthesis; UDP-N-acetyl-alpha-D-glucosamine from N-acetyl-alpha-D-glucosamine 1-phosphate: step 1/1. Present with 5480 molecules/cell in log phase SD medium. Belongs to the UDPGP type 1 family.