SUMMARY PARAGRAPH for GNA1
UDP-N-acetyl-D-glucosamine (UDP-GlcNAc) is the source of the first two GlcNAc moieties added during N-linked glycosylation of proteins and provides GlcNAc for synthesis of GPI anchors. In yeast, it is synthesized from fructose-6-phosphate (F6P) by the consecutive action of Gfa1p, Gna1p, Pcm1p, and Qri1p, although a different pathway (4, 5) is used in bacteria. UDP-GlcNAc is also the building block from which chitin, a linear polymer of beta-1,4-N-acetylglucosamine, is constructed. Chitin is a component of the cell wall deposited as a ring around the neck of the growing bud during cell division. Bud scars, the remnants of the chitinous primary septum seen on the surface of mother cells after division, are the primary repository of chitin (reviewed in 6).
GNA1 encodes glucosamine-6-phosphate acetyltransferase (EC 22.214.171.124), which adds an acetyl group to GlcN6P in the UDP-GlcNAc biosynthesis pathway (2). GNA1 is an essential gene (2). As with PCM1 and QRI1, conditional depletion of Gna1p causes cells to swell and lyse (1, 2) and to form strings of four to five cells (1). The S. pombe homolog spPAT1 complements deletion of GNA1 (1).
Last updated: 2005-07-01