1. Although glycoproteins with less than 1% of sialic acid (fibrinogen, lipoproteins, gamma-globulins) interact electrostatically with chondromucoprotein to form insoluble complexes, interaction with glycoproteins containing larger amounts of sialic acid (orosomucoid, urine glycoprotein, seromucoid, fraction VI) was electrostatically impossible. Reasons for this are discussed. 2. The latter gly...

Glycoproteins in the plasma membrane of rat hepatoma cells were labeled at their externally exposed tyrosine residues with 131I and at their galactose and sialic acid residues with 3H. The degradation of both isotopes in the total cell protein fraction, in glycoproteins purified by concanavalin A, and in glycoproteins separated on two-dimensional gels was determined. Similarly, the total cellul...

of human erythrocyte ghosts were solubilized with 0.5yc Triton X-100 in 56 mM sodium borate, pH 8.0. This procedure solubilized 51% of the membrane protein, 81% of the sialic acid, 89% of the receptors for the Agaricus bisporus lectin and 70 to 75% of the wheat germ agglutinin and Ricinus communis lectin receptors. The solubilized glycoproteins were then separated by affinity chromatography on ...