Galactose-containing polysaccharides from Dictyostelium mucoroides as possible acceptor molecules for cell-type specific galactosyl transferase.

Dictyostelium discoideum has polysaccharides that accept galactose residues by the action of cell-type-specific galactosyl transferase. This paper describes partial purification of the major galactose-accepting polysaccharide that was isolated from the related strain, Dictyostelium mucoroides and proposes its plausible carbohydrate sequences. The most potent acceptor activity was observed in the neutral and Ricinus communis agglutinin (RCA-60) bound galactosaminoglycan, consisting of galactose (Gal) and galactosamine (GalN). However, the acceptor polysaccharides are highly heterogeneous in the reactivity with RCA-120 and in molecular mass. The peak fraction was analyzed by (1)H- and (13)C-NMR studies, methylation analysis, beta-D-galactosidase digestion, controlled Smith degradation and reducing terminal analysis. Based on these results, we tentatively propose the following novel type of the common carbohydrate sequences as the acceptor polysaccharides. [abstract - see text].