Oligosaccharide heterogeneity of glycoproteins sulfated during the vegetative growth of Dictyostelium discoideum

Davis SJ. (1988), J Cell Biochem. 38, 77-86

Abstract

Macromolecules are sulfated during the vegetative growth of Dictyostelium discoideum. A characterisation of the structures of sulfated oligosaccharides associated with these macromolecules indicates that the oligosaccharides are heterogeneous. Endoglycosidase and pronase digestion were used with gel-filtration chromatography to obtain two different oligosaccharide fractions and a glycopeptide fraction; these were further characterised by ion-exchange and lectin-affinity chromatography and by acid hydrolysis. The data indicate that up to 43% of the sulfate is associated with typical N-linked oligosaccharides, that up to 5% is associated with N-linked oligosaccharides that are either very large or extremely highly charged, and that the remaining sulfate is associated with oligosaccharides non-N-linked to protein. Each fraction was also shown to be heterogeneous at most other structural levels. Electrophoretic analyses following the endoglycosidase and pronase treatments indicated that all of the macromolecules are glycoproteins and suggested further that at least two of the oligosaccharide fractions are located on different groups of glycoproteins.

Key figure

Electrophoretic analysis of the effects of PNGase F and pronase on the [³⁵S] sulfate-labeled macromolecules. [³⁵S] sulfate-labeled macromolecules from vegetative D. discoideum strain NP73 amoebae were treated with PNGase F and pronase as described in “Materials and Methods.” Aliquots containing approximately 20,000 cpm of the original (lane 1), PNGase F-(lane 2), and pronase-(lane 3) treated preparations were analysed by SDS polyacrylamide gel electrophoresis. A fluorograph of the gel is shown. PNGase F-sensitive macromolecules are indicated (arrowheads).