A subclass of cell surface carbohydrates revealed by a cho mutant with two glycosylation mutations

Pamela Stanley, Subha Sundaram, Sandra Sallustio

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

A novel lectin-resistance phenotype was displayed by a LEC10 Chinese hamster ovary (CHO) cell mutant that was selected for resistance to the erythroagglutinin, E-PHA. Biochemical and genetic analyses revealed that the phenotype results from the expression of two glycosylation mutations, LEC10 and lec8. The LEC10 mutation causes the appearance of N-acetylglucosaminyltransferase III (GlcNAc-TIII) activity and the production of N-linked carbohydrates with a bisecting GlcNAc residue. The lec8 mutation inhibits translocation of UDP-Gal into the Golgi lumen and thereby dramatically reduces galactosylation of all glycoconjugates. This reduction in galactose addition does not, however, cause Lec8 mutants to be very resistant to the galactose-binding lectin, ricin. By contrast, the double mutant OLEC10.Lec8 behaved like a LEC10 mutant and was highly resistant to ricin. Based on structural studies of cellular glycopeptides as well as glycopeptides of the G glycoprotein of vesicular stomatitis virus grown in mutant cells, it appears that the ricin resistance of LEC10.Lec8 cells is due to the presence of a small number of Gal residues on branched, N-linked carbohydrates that also carry the bisecting GlcNAc residue. Labelling of N-linked cellular carbohydrates with [3H]galactose was found to occur at a low level for a wide spectrum of cellular glycoproteins in independent Lec8 mutants. Studies of the LEC10.Lec8 mutant have, therefore, led to the identification of a subset of structures that are acceptors for Gal when intra-Golgi UDP-Gal levels are limiting. This mutant also illustrates the potential for regulating cell surface recognition by carbohydrate-binding proteins by altering the expression of a single glycosyltransferase such as GlcNAc-TIII.

Original languageEnglish (US)
Pages (from-to)307-314
Number of pages8
JournalGlycobiology
Volume1
Issue number3
DOIs
StatePublished - Jun 1991

Fingerprint

Glycosylation
Ricin
Carbohydrates
Mutant
Mutation
Uridine Diphosphate
Glycopeptides
beta-1,4-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase
Galactose
Glycoproteins
Cell
Galectins
Glycosyltransferases
Glycoconjugates
Lectin
Phenotype
Viruses
Lectins
Labeling
Vesicular Stomatitis

Keywords

  • Carbohydrates
  • Cell surface
  • LEC10.Lec8 mutant
  • Lectin resistance

ASJC Scopus subject areas

  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Public Health, Environmental and Occupational Health
  • Neuropsychology and Physiological Psychology
  • Hematology
  • Biochemistry

Cite this

A subclass of cell surface carbohydrates revealed by a cho mutant with two glycosylation mutations. / Stanley, Pamela; Sundaram, Subha; Sallustio, Sandra.

In: Glycobiology, Vol. 1, No. 3, 06.1991, p. 307-314.

Research output: Contribution to journalArticle

Stanley, Pamela ; Sundaram, Subha ; Sallustio, Sandra. / A subclass of cell surface carbohydrates revealed by a cho mutant with two glycosylation mutations. In: Glycobiology. 1991 ; Vol. 1, No. 3. pp. 307-314.
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AB - A novel lectin-resistance phenotype was displayed by a LEC10 Chinese hamster ovary (CHO) cell mutant that was selected for resistance to the erythroagglutinin, E-PHA. Biochemical and genetic analyses revealed that the phenotype results from the expression of two glycosylation mutations, LEC10 and lec8. The LEC10 mutation causes the appearance of N-acetylglucosaminyltransferase III (GlcNAc-TIII) activity and the production of N-linked carbohydrates with a bisecting GlcNAc residue. The lec8 mutation inhibits translocation of UDP-Gal into the Golgi lumen and thereby dramatically reduces galactosylation of all glycoconjugates. This reduction in galactose addition does not, however, cause Lec8 mutants to be very resistant to the galactose-binding lectin, ricin. By contrast, the double mutant OLEC10.Lec8 behaved like a LEC10 mutant and was highly resistant to ricin. Based on structural studies of cellular glycopeptides as well as glycopeptides of the G glycoprotein of vesicular stomatitis virus grown in mutant cells, it appears that the ricin resistance of LEC10.Lec8 cells is due to the presence of a small number of Gal residues on branched, N-linked carbohydrates that also carry the bisecting GlcNAc residue. Labelling of N-linked cellular carbohydrates with [3H]galactose was found to occur at a low level for a wide spectrum of cellular glycoproteins in independent Lec8 mutants. Studies of the LEC10.Lec8 mutant have, therefore, led to the identification of a subset of structures that are acceptors for Gal when intra-Golgi UDP-Gal levels are limiting. This mutant also illustrates the potential for regulating cell surface recognition by carbohydrate-binding proteins by altering the expression of a single glycosyltransferase such as GlcNAc-TIII.

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