The biosynthesis of mannose-containing glycoproteins: A possible lipid intermediate

These studies compare the secretory pathways of newly formed rat serum glycoproteins and albumin by studying their submicrosomal localization at early times after the beginning of their synthesis and also by determining the submicrosomal site of incorporation of N-acetylglucosamine, mannose, galactose, and leucine into protein . N-acetylglucosamine, mannose, and galactose were only incorporated in vitro into proteins from membraneattached polysomes and not into proteins from free polysomes . Mannose incorporation occurred in the rough endoplasmic reticulum, was stimulated by puromycin but not by cycloheximide, and 90% of the mannose-labeled protein was bound to the membranes .Galactose incorporation, by contrast, occurred in the smooth microsome fraction and 89% of the radioactive protein was in the cisternae . Albumin was mostly recovered (98%0 ) in the cisternae, with negligible amounts in the membranes . To determine whether the radioactive sugars were being incorporated into serum proteins or into membrane protein, the solubilized in vivo-labeled proteins were treated with specific antisera to rat serum proteins or to albumin. Immunoelectrophoresis of the "C-labeled leucine membrane and cisternal proteins showed that the membranes contained radioactive serum glycoprotein but no albumin, while the cisternal fraction contained all of the radioactive albumin and some glycoproteins . The results indicate that newly formed serum glycoproteins remain attached to the membranes of the rough endoplasmic reticulum after they are released from the membrane-attached polysomes, while albumin passes directly into the cisternae .

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“…Wagner and Cynkin (27) and Caccam et al . (28) do not find incorporation into the rough ER . Our studies agree with those of Molnar et al .…”

Section: Discussionmentioning

confidence: 75%

The Secretory Pathways of Rat Serum Glycoproteins and Albumin

Redman

Cherian

1972

The Journal of Cell Biology

147

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“…In animal tissues an enzyme has been described which catalyzes mannose transfer from GDP-mannose to a lipid. 4 In the course of work with UDPG it has now been found that liver contains enzymes which catalyze the following reactions: UDPG + acceptor lipid G-acceptor lipid + UDP (1) G-acceptor lipid + protein acceptor lipid + G-protein…”

mentioning

confidence: 99%

Dolichol Monophosphate Glucose: An Intermediate in Glucose Transfer in Liver

Behrens¹,

Leloir²

1970

Proc. Natl. Acad. Sci. U.S.A.

243

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“…The studies of Robbins et al, Osborn [24], yeast [25,26], and higher plants [19,27] are built by transfer of mannose units via a lipid intermediate to the growing polysaccharide. Lipid intermediates have also been implicated in the biosynthesis of rat-liver glycoproteins [28,29], of wall polymer poly(N-acetylglucosamine 1-phosphate) of Staphylococcus lactis [30], and of capsular polysaccharide of Aerobaeter aerogenes [31]. It was also shown that in Salmonella of groups B and E [32- yet been determined whether all the glucose residues are within the polysaccharide chain or are linked as side residues to a mannose backbone.…”

Section: Studies On the Mechanism Of Incorporationmentioning

confidence: 99%

Studies of the Biosynthesis of the O9 Antigen from Escherichia coli O9:K30(A):H12

Fitzgerald-Chandler¹,

Jann²

1971

European Journal of Biochemistry

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into acetic-acid precipitates has been studied with a preparation from cells ground with alumina. The time-course of mannose incorporation was biphasic (rapid reaction for 2-5min followed by a slower, linear reaction for 5-20min) and the incorporation was stimulated by uridine diphosphate glucose (UDP-Glc) during the early part of the reaction. The reactions (mannose incorporation after 2 min and 15 min, & UDP-Glc) were nevertheless proportional to protein concentration. [14C]Glucose was incorporated into acetic-acid precipitates from UDP-[14C]GIc and this reaction was slightly stimulated by GDP-Man. Radioactivity from GDP-[14C]Man was incorporated into butanol extracts and the early part of the reaction (2-5 min) was markedly stimulated by UDP-Glc. Bacitracin did not inhibit the incorporation of mannose into acetic-acid precipitates in the early part of the reaction, but did inhibit incorporation about 2001, between 5 and 30 min.Larger-scale incubation mixtures were extracted with 4501, aqueous phenol. The product was of high molecular weight as indicated by Sephadex G-100 chromatography and yielded a single radioactive peak corresponding to mannose after total hydrolysis and paper chromatography. This high-molecular-weight product precipitated with anti-09 antiserum in an antigen-binding assay, indicating that it was serologically active. Thus, it is likely that the 0 9 antigen of E . wli 0 9 : K30(A) : H12 is synthesized from GDP-Man and UDP-Glc through a butanol-extractable (lipid-linked) intermediate. Reactions appear to be analogous to those described for lipopolysaccharide biosynthesis in Xalmonella.I n Escherichia coli, 150 different 0 antigens are known. These are lipopolysaccharides and have been typed according to their sugar composition [l]. I n addition to the O-antigenic lipopolysaccharides about 100 different K antigens are known [2]. Combinations of these surface antigens on the bacterial cell give rise to an enormous variety of E . coli serotypes. These combinations, however, are subject to a restriction not yet understood. All K antigens of the A-type [Z], i.e. such K antigens which are true serologically-distinct capsules of unique acidic polysaccharides and which are readily lost by mutation, occur only with E.coli cells bearing either antigen 08 or 09. We became interested in studying the biosynthesis of O-antigenic lipopolysaccharides and Kantigenic acidic polysaccharides of E . coli strains 0 8 and 0 9 to investigate the relationship of the K and 0 antigens.

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The biosynthesis of mannose-containing glycoproteins: A possible lipid intermediate

Cited by 144 publications

References 14 publications

The Secretory Pathways of Rat Serum Glycoproteins and Albumin

The Secretory Pathways of Rat Serum Glycoproteins and Albumin

Dolichol Monophosphate Glucose: An Intermediate in Glucose Transfer in Liver

Studies of the Biosynthesis of the O9 Antigen from Escherichia coli O9:K30(A):H12

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