Glycosaminoglycans are integral constituents of renal glomerular basement membrane

Basement membranes from canine renal glomeruli were isolated following osmotic lysis and sequential detergent treatment. Substantial amounts of uronic acid in unfractionated membranes were demonstrated with the carbazole and orcinol reactions. About 10–15% of basement membrane uronic acid was solubilized with neutral salt solutions. Denaturation in 8M urea solubilized ?70% of the uronic acid but only ?10% of basement membrane hydroxyproline; the latter was solubilized after reduction and alkylation. Uronic acid containing glycoprotein isolated by denaturation did not bind to carboxymethylcellulose and migrated as a high molecular weight band on SDS-gel electrophoresis. The ability of isolated rat glomeruli to incorporate radioactive sulfate $\text{in}\text{vitro}$ was demonstrated. These findings indicate that sulfated glycosaminoglycans are integral components of glomerular basement membrane.