We have found that
polyacrylamide gel electrophoresis in 3%
gels in the presence of
sodium dodecyl sulfate is suitable for the separation of cellular
glycoproteins having molecular weights ranging from 200,000 to 1,000,000. The
gels secured on a rigid support (Gelbond) allow blotting techniques with
lectins and
antibodies for the detection of
glycoproteins. Using these methods we have separated lysates of HT-29 human colon
carcinoma cells and detected at least four distinct high molecular weight
sialoglycoproteins having molecular weights of 900,000, 740,000, 560,000, and 450,000. The expression of the 900,000 component, as revealed by
wheat germ agglutinin binding, was much higher in a subline of HT-29 cells established from liver
metastases in a nude mouse than it was in the parental cells. The relative intensity of
wheat germ agglutinin binding to these four
sialoglycoprotein components differs depending upon their growth phase in vitro. These
glycoproteins were also detectable by the binding of
peanut agglutinin, provided the
glycoproteins were previously treated in the
gels with mild
acid to remove the
sialic acid from their
carbohydrate chains, suggesting that
mucin-type
carbohydrate chains are present on these
glycoproteins. The same set of
glycoproteins can be detected by metabolic labeling of the cells with [3H]
glucosamine in tissue culture. Very similar
glycoprotein profiles are revealed by metabolic labeling of fresh colon
carcinoma tissues with [3H]
glucosamine in vitro.