Glycosyltransferase Activities in Golgi Complex and Endoplasmic Reticulum Fractions Isolated from African Trypanosomes

Highly enriched Golgi complex and endoplasmic reticulum fractions were isolated from total microsomes obtained from Trypanosoma brucei, Trypanosoma congolense, and Trypanosoma vivax, and tested for glycosyltransferase activity. Purity of the fractions was assessed by electron microscopy as well as b...

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Bibliographic Details
Published in:The Journal of cell biology 1984-08, Vol.99 (2), p.569-577
Main Authors: Grab, D. J., Ito, S., Kara, U. A. K., Rovis, L.
Format: Article
Language:English
Subjects:
Animals
Biochemistry. Physiology. Immunology. Molecular biology
Biological and medical sciences
Carbohydrates
Cell membranes
Endoplasmic reticulum
Endoplasmic Reticulum - enzymology
Endoplasmic Reticulum - ultrastructure
Enzymes
Fundamental and applied biological sciences. Psychology
Glycoproteins
Golgi apparatus
Golgi Apparatus - enzymology
Golgi Apparatus - ultrastructure
Hexosyltransferases - metabolism
Histocytochemistry
Intracellular Membranes - enzymology
Intracellular Membranes - ultrastructure
Membrane glycoproteins
Microscopy, Electron
Microsomes
Microsomes - enzymology
Microsomes - ultrastructure
Parasitism
Protozoa
Species Specificity
Trypanosoma - enzymology
Trypanosoma - ultrastructure
Trypanosoma brucei brucei - enzymology
Trypanosoma congolense - enzymology
Trypanosome
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Summary:Highly enriched Golgi complex and endoplasmic reticulum fractions were isolated from total microsomes obtained from Trypanosoma brucei, Trypanosoma congolense, and Trypanosoma vivax, and tested for glycosyltransferase activity. Purity of the fractions was assessed by electron microscopy as well as by biochemical analysis. The relative distribution of all the glycosyltransferases was remarkably similar for the three species of African trypanosomes studied. The Golgi complex fraction contained most of the galactosyltransferase activity followed by the smooth and rough endoplasmic reticulum fractions. The dolichol-dependent mannosyltransferase activities were highest for the rough endoplasmic reticulum, lower for the smooth endoplasmic reticulum, and lowest for the Golgi complex. Although the dolichol-independent form of N-acetylglucosaminyltransferase was essentially similar in all the fractions, the dolichol-dependent form of this enzyme was much higher in the endoplasmic reticulum fractions than in the Golgi complex fraction. Inhibition of this latter activity in the smooth endoplasmic reticulum fraction by tunicamycin A1suggests that core glycosylation of the variable surface glycoprotein may occur in this organelle and not in the rough endoplasmic reticulum as previously assumed.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.99.2.569