Occurrence of O-glycosidically peptide-linked oligosaccharides of poly-N-acetyllactosamine type (erythroglycan II) in the I-antigenically active Sendai virus receptor sialoglycoprotein GP-2.

Unique high molecular weight (M.W. 4,000-9,000) sugar chains termed erythroglycan II have been obtained from alkali/sodium borohydride digests of I-active asialoglycoprotein derived from sialoglycoprotein GP-2, which was isolated recently from bovine erythrocyte membranes as Sendai virus receptor (Suzuki, Y. et al. (1983) J. Biochem. 93, 1621-1633; (1984) ibid, 95, 1193-1200). It was found that these sugar chains comprise about 40% of total alkali-labile oligosaccharides of asialo GP-2 and contain endo-beta-galactosidase (Flavobacterium keratolyticus)-resistant highly branched and heterogeneous oligosaccharides of poly-N-acetyllactosamine type which are linked O-glycosidically to the peptide backbone through N-acetylgalactosamine. Erythroglycan II also contains endo-beta-galactosidase-susceptible straight terminal polylactosaminyl side chains. A major oligosaccharide released by the enzyme cochromatographed with Gal beta 1-4GlcNAc beta 1-3Gal. Inhibitory activity of Sendai virus-mediated hemagglutination and the receptor activity for the virus were reduced significantly but not completely by the endo-beta-galactosidase. These results indicate that both linear and branched sialosylpolylactosamine sequences in erythroglycan II are important for the reception of the virus into the target cells.