Isolation and characterization of an epithelial basement membrane glycoprotein from murine kidney and further characterization of an epithelial basement membrane glycoprotein secreted by murine teratocarcinoma cells in vitro.

A glycoprotein component of epithelial basement membranes (EBM) has been isolated from murine kidney homogenates by extraction with 0.05 M phosphate buffer, pH 7.2, precipitation with (NH4)2SO4 and chromatography on controlled pore glass. Antiserum produced against this glycoprotein reacts specifically with the basement membranes of renal glomeruli and tublules. The EBM glycoprotein of renal origin is antigenically identical with a glycoprotein component of epithelial basement membrane secreted by a murine teratocarcinoma grown in vitro, and the amino acid composition of the two EBM glycoproteins is markedly similar. Both glycoproteins were isolated as high molecular weight aggregates. Disaggregation with sodium dodecyl sulfate and 2-mercaptoethanol resulted in release of monomers of 32 000 and 34 000 daltons for kidney EBM glycoprotein and teratocarcinoma EBM glycoprotein, respectively. The difference in molecular weight is apparently due to increased amounts of fucose, mannose, N-acetylglucosamine and sialic acid in the glycoprotein secreted by the teratocarcinoma. In addition, both EBM glycoproteins contain galactose, glucose and N-acetylgalactosamine.