Subcellular localization of glycosidases and glycosyltransferases involved in the processing of N-linked oligosaccharides

Journal Article · Sun Nov 01 00:00:00 EST 1987 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.85.3.741· OSTI ID:5642213

Sturm, A; Johnson, K D; Szumilo, T; Elbein, A D; Chrispeels, M J

Using isopycnic sucrose gradients, we have ascertained the subcellular location of several enzymes involved in the processing of the N-linked oligosaccharides of glycoproteins in developing cotyledons of the common bean, Phaseolus vulgaris. All are localized in the endoplasmic reticulum (ER) or Golgi complex as determined by co-sedimentation with the ER marker, NADH-cytochrome c reductase, or the Golgi marker, glucan synthase I. Glucosidase activity, which removes glucose residues from Glc/sub 3/Man/sub 9/(GlcNAc)/sub 2/, was found exclusively in the ER. All other processing enzymes, which act subsequent to the glucose trimming steps, are associates with Golgi. These include mannosidase I (removes 1-2 mannose residues from Man/sub 6-9/(GlcNAc)/sub 2/), mannosidase II (removes mannose residues from GlcNAcMan/sub 5/(GlcNAc)/sub 2/), and fucosyltransferase (transfers a fucose residue to the Asn-linked GlcNAc of appropriate glycans). The authors have previously reported the localization of two other glycan modifying enzymes (GlcNAc-transferase and xylosyltranferase activities) in the Golgi complex. Attempts at subfractionation of the Golgi fraction on shallow sucrose gradients yielded similar patterns of distribution for all the Golgi processing enzymes. Subfractionation on Percoll gradients resulted in two peaks of the Golgi marker enzyme inosine diphosphatase, whereas the glycan processing enzymes were all enriched in the peak of lower density. These results do not lend support to the hypothesis that N-linked oligosaccharide processing enzymes are associated with Golgi cisternae of different densities.

• Research Organization: Univ. of California, San Diego, CA (United States)
• OSTI ID: 5642213
• Journal Information: Plant Physiol.; (United States), Vol. 85:3
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
GLYCOSYL HYDROLASES
ENZYME ACTIVITY
SUBCELLULAR DISTRIBUTION
GLYCOSYL TRANSFERASES
OLIGOSACCHARIDES
METABOLISM
BIOLOGICAL MARKERS
ENDOPLASMIC RETICULUM
PHASEOLUS
BACTERIA
CARBOHYDRATES
CELL CONSTITUENTS
DISTRIBUTION
ENZYMES
HYDROLASES
LEGUMINOSAE
MICROORGANISMS
ORGANIC COMPOUNDS
ORGANOIDS
PLANTS
RHIZOBIUM
SACCHARIDES
TRANSFERASES
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)