UDPGlcNAc pyrophosphorylase catalayzes the synthesis of UDPGlcNAc.
UDP-N-acetylglucosamine (UDPGlcNAc) pyrophosphorylase (UAP) (also named GlcNAc1P uridyltransferase), catalyzes the reversible conversion of UTP and GlcNAc1 to PPi and UDPGlcNAc. UDP-N-acetylglucosamine (UDPGlcNAc), the activated form of GlcNAc, is a key precursor of N- and O-linked glycosylations. It is essential for the synthesis of chitin (a major component of the fungal cell wall) and of the glycosylphosphatidylinositol (GPI) linker which anchors a variety of cell surface proteins to the plasma membrane. In bacteria, UDPGlcNAc represents an essential precursor for both peptidoglycan and lipopolysaccharide biosynthesis. Human UAP has two isoforms, resulting from alternative splicing of a single gene and differing by the presence or absence of 17 amino acids. UDPGlcNAc pyrophosphorylase shares significant sequence and structure conservation with UDPglucose pyrophosphorylase.