Common peptide epitopes in glycophorin and the endothelial sialoglycoprotein gp60*1

Abstract Polyclonal anti-serum made against murine glycophorin gp3 (αgp) recognizes the endothelial albumin binding glycoprotein, gp60. In this study, we investigated the nature (peptide vs. carbohydrate) of the common epitope. First, a new technique was developed to remove oligosaccharides from glycoproteins that were first immobilized on filters and then subjected to β-elimination. When greater than 90% of the glycans of gp60 were removed, αgp still recognized gp60 without apparent loss of affinity. Second, we used brefeldin A to accumulate unglycosylated glycophorin precursors in order to affinity-purify peptide-specific αgp immuno-globulins; these antibodies recognized gp60. Finally, αgp recognized from in vitro translations a 48 kDa putative polypeptide precursor of gp60. These different approaches indicate that gp60 and gp3 have at least one common epitope in their peptide backbones.