Synthesis of cell-wall glycoproteins and their characterization in oat coleoptiles.
D-[U-14C]Glucosamine was rapidly taken up by oat coleoptile segments and metabolized to radioactive UDP-N-acetylglucosamine, which acted as specific glycosyl donor for the synthesis of glycolipids and cytosolic, membrane-bound and cell-wall glycoproteins. Cell-wall glycoproteins were solubilized from the walls by either cell-wall-degrading enzymes or chemical extractants. The solubilized cell-wall glycoproteins in the presence of peptide N-glycosidase F released oligosaccharide chains higher than seven glycosidic residues. The combined action of peptide N-glycosidase F and N-acetyl-beta-D-glucosaminidase on cell-wall glycoproteins indicated the presence of N-acetylglucosamine residues beta-1,2-linked to mannose. Less than 9% of the radioactive oligosaccharide chains was released from the solubilized cell-wall glycoproteins when treated with 0.5 M NaOH at 20 degrees, whereas more than 45% of the radioactivity was released in the presence of 1 M NaOH at 50 degrees. The high hydrolytic sensitivity of cell-wall glycoproteins to peptide N-glycosidase F, N-acetyl-beta-D-glucosaminidase and NaOH at 50 degrees indicated that most N-acetylglucosamine residues were incorporated into N-linked cell-wall glycoproteins. Further evidence of this was obtained by the use of inhibitors of biosynthesis and processing of N-linked glycoproteins.
Pacoda
D
D
Dipartimento di Biologia, Università di Lecce, Italy.
Montefusco
A
A
Piro
G
G
Dalessandro
G
G
D000118:Acetylglucosaminidase / Q000378:metabolism; D000581:Amidohydrolases / Q000378:metabolism; D018554:Avena / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002473:Cell Wall / Q000378:metabolism*; D005944:Glucosamine / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D011499:Protein Processing, Post-Translational
D002250:Carbon Radioisotopes; D008562:Membrane Glycoproteins; D000118:Acetylglucosaminidase; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D005944:Glucosamine