J. Biol. Chem., Vol. 255, Issue 8, 3266-3269, Apr, 1980
Presence of erythroglycan on human K-562 chronic myelogenous leukemia- derived cells
SJ Turco, JS Rush and RA Laine
Total glycopeptides from human K-562 cells, labeled metabolically with
[3H]glucosamine or [3H]mannose, were prepared by extracting the cells with
organic solvents to remove lipids and by digesting the residue with
pronase. 3H-labeled glycopeptides were fractionated on Sephadex G- 50
revealing a high molecular weight fraction (Mr = 7,000 to 11,000),
comprising approximately 10% of the [3H]glucosamine and 25% of the
[3H]mannose label. Digestion of this glycopeptide fraction with endo-
beta-galactosidase from Escherichia freundii, specific for a repeating
structure of Gal(beta 1 leads to 4)GlcNAc(beta 1 leads to 3), results in
the following four products as resolved by Bio-Gel P-2 gel filtration: 1) a
disaccharide with the structure beta-2-deoxy-2- acetamidoglucosyl leads to
beta-galactose; 2) a trisaccharide with the structure beta-galactosyl leads
to beta-2-deoxy-2-acetamidoglucosyl leads to beta-galactose; 3) a
tetrasaccharide with the sequence alpha-N- acetylneuraminyl leads to
beta-galactosyl leads to beta-2-deoxy-2- acetamidoglucosyl leads to
beta-galactose; and 4) a larger, complex fragment which contains mannose
and beta-2-deoxy-2-acetamidoglucose and which is probably the protein
linkage region. In addition, visualization of radiolabeled glycoproteins by
fluorography on polyacrylamide gels revealed a 105,000-dalton "Band 3"-like
glycoprotein and other bands that were sensitive to endo-beta-
galactosidase. These results indicate that the K-562 cell line bears a
glycopeptide, erythroglycan, which has been found on erythrocytes, and that
this polymer is expressed mainly in the fetal form as a linear chain.