High impact information on Man5GlcNAc2

• Immunoprecipitation showed that Yos9 specifically associated with misfolded carboxypeptidase Y (CPY*), an ERAD substrate, but only when it carried Man8GlcNAc2 or Man5GlcNAc2 N-glycans [1].
• In this paper we show that at both 32 and 39 degrees C in two mutant cell lines accumulate a truncated version, Man5GlcNAc2, of the normal lipid-linked precursor oligosaccharide, Glc3Man9GlcNAc2 [2].
• G protein is trimmed from the high mannose form to the man5GlcNAc2 form without the appearance of the intermediate man GlcNAc2 oligosaccharide species, as is observed in vivo [3].
• VP7 on mature virus was processed to Man5GlcNAc2 [4].
• The protein-bound oligomannose precursor Man8GlcNAc2-, arriving in the Golgi after the initial trimming in the endoplasmic reticulum (ER), first undergoes a series of preprocessing steps to yield Man5GlcNAc2- in animals and plants or Man13-15GlcNAc2- in yeast [5].

Biological context of Man5GlcNAc2

• Thus, the vast majority of the N-linked glycosylation in the ER of alg3 yeast (> 75%) occurs by transfer of Man5GlcNAc2 without prior addition of the 3 glucoses normally found on the lipid-linked precursor [6].
• Phosphorylation of the Man5GlcNAc2 oligosaccharide could not be detected even though this was the major species on the native uteroferrin [7].
• The labeling kinetics and compositions of the lipid-linked oligosaccharides were examined, and the results indicate that lipid-linked Man5GlcNAc2 is rapidly assembled (< 1.5 min) and then extended (< 2.5 min) to Glc3Man9GlcNAc2 via the intermediate Man8GlcNAc2 [8].
• The delta och1 mnn1 alg3 mutants accumulated Man5GlcNAc2 and Man8GlcNAc2 in total cell mannoprotein, confirming the lack of outer chain addition to the incomplete corelike oligosaccharide and the leaky phenotype of the alg3 mutation [9].

Anatomical context of Man5GlcNAc2

• A mutation in glycoprotein processing inhibitor-resistant (PIR) Chinese hamster ovary (CHO) cells was previously shown to result in a block at the Man5GlcNAc2 stage of the dolichol-oligosaccharide biosynthetic pathway (Lehrman, M.A., and Zeng, Y. (1989) J. Biol. Chem. 264, 1584-1593) [10].
• Furthermore, although the temperature requirements of the reactions for the control CHO and PIR membranes were similar, Man5GlcNAc2-elongating activity in CHO membranes was inhibited by alkaline pH treatment, whereas this treatment irreversibly stimulated the activity in PIR membranes [10].
• Man5GlcNAc2 was a second major rate-limiting step in processing of free alpha-subunits only and accumulated in distal smooth endoplasmic reticulum/Golgi apparatus [11].
• In this paper, we demonstrate that the alpha1,2 mannosidase, which is involved in the processing of Man5GlcNAc2 into Man4GlcNAc2, is located in the rough endoplasmic reticulum [12].

Associations of Man5GlcNAc2 with other chemical compounds

• The in vitro activity of wild type hTSH expressed in CHO-LEC2 cells (sialic acid-deficient oligosaccharides), CHO-LEC1 cells (Man5GlcNAc2 intermediates), and 293 cells (sulfated oligosaccharides) was 5-8-fold higher than of wild type from CHO-K1 cells [13].
• From immuno- and affinodetections on blots, chromatography, nuclear magnetic resonance, and glycosidase sequencing data, we show that Arabidopsis proteins are N-glycosylated by high-mannose-type N-glycans from Man5GlcNAc2 to Man9GlcNAc2, and by xylose- and fucose (Fuc)-containing oligosaccharides [14].
• Asparagine-linked glycosylation was altered such that 3E11 cells synthesized primarily a truncated oligosaccharide, Man5GlcNAc2, perhaps due to the reduced amount of mannosylphosphoryldolichol relative to wild-type cells [15].

Gene context of Man5GlcNAc2

• The inactivation of the nonessential ALG3 gene results in the accumulation of lipid-linked Man5GlcNac2 and protein-bound carbohydrates which are completely Endo H resistant [16].
• Here we describe several major differences, on both structural and functional levels, between human THP (hTHP) and pig THP (pTHP). pTHP contains a much higher proportion (47%) of Man5GlcNAc2 than does hTHP (8%) [17].
• Acidic complex-type chains were found at all three N-glycosylation sites, while Man5GlcNAc2 was found at Asn83 and Asn191, but there was very little of this sperm-ligand active chain at Asn527 in the ZP domain of ZPA [18].
• The San Juan G protein with Man5GlcNAc2 oligosaccharides aggregated at 40 degrees C but not at 30 degrees C. The Orsay G protein with Man5GlcNAc2 oligosaccharides and both proteins containing Man8GlcNAc2 oligosaccharides did not aggregate at either temperature [19].
• The glycosylation pattern of the insect cell expressed recombinant human plasminogen showed considerable microheterogeneity, with identifiable high-mannose carbohydrate (Man9GlcNAc2) and truncated high-mannose oligosaccharide (Man5GlcNAc2, Man4GlcNAc2, and Man3GlcNAc2) [20].

Analytical, diagnostic and therapeutic context of Man5GlcNAc2

• High-performance liquid chromatography analyses showed that the structure of the asparagine-linked oligosaccharide chain attached to residue Asn79 was Man5GlcNAc2, and that bound to residue Asn188 was Man5GlcNAc2 and Man6GlcNAc2 [21].

References