Analysis of Glycoprotein-Bound Carbohydrates from Pluripotent Embryonal Carcinoma Cells by Pokeweed Agglutinin–Agarose1

Abstract

Embryoglycan is the high-molecular-weight poly-N-acetyllactosamine characteristically and abundantly present in early embryonic cells. Among lectins reacting with poly-N-acetyllactosamines pokeweed agglutinin (PWA) was found to be most useful in analyzing glycoproteins from HM-1 pluripotent embryonal carcinoma (EC) cells, since virtually all glycoproteins carrying embryoglycan in these cells could be isolated by affinity chromatography on PWA-agarose. Furthermore almost all of embryoglycan from HM-1 cells bound to PWA-agarose. Since PWA-agarose used for the present study was confirmed to bind branched but not linear poly-N-acetyllactosamines, the above result indicated that embryoglycan lacking branched poly-N-acetyllactosaminyl chain was scarcely present in these cells. The same approach was used as a mean to show that embryoglycan with Lotus tetragonolobus agglutinin receptor activity also usually has the branched poly-N-acetyllactosamine structure in EC cells. Glycoprotein fractions from PYS-2 parietal endoderm cells and from STO fibroblasts also bound to PWA-agarose. However, the ratio of PWA binding fraction to the total [14C]galactose-labeled glycoproteins was less in these cells as compared to the value in EC cells, and the poly-N-acetyllactosamines from these cells exhibited lower molecular weights than embryoglycan. These results are consistent with our proposal that the complexity and abundance of poly-N-acetyllactosamines distinguishes EC cells from most other cells.