Characterization of heparan sulfate-proteoglycan of glomerular basement membranes

Native and de novo synthesized heparan sulfate-proteoglycan (HS-PG) of basement membranes from isolated whole glomeruli were characterized. Sepharose CL-6B chromatograms of [35S]sulfate-labeled de novo synthesized HS-PG extracted from whole glomeruli indicated identical molecular weight characteristics to that isolated from purified basement membranes (Mr of intact HS-PG approximately equal to 130,000; Mr of chains approximately equal to 25,000). Electron microscopic autoradiography showed that almost all radioactive grains were localized to the basement membranes proper. The estimated Mr of core protein approximately equal to 18,000. The sedimentation coefficient of native intact HS-PG was 5.56 S, corresponding to a Mr between 150,000-250,000, a value in accord with gel filtration data on newly synthesized HS-PG. Physicochemical characteristics of HS-PG of native functional basement membranes differed remarkably from that isolated from the basement membrane-producing tumor, Engelbreth-Holm-Swarm sarcoma.