Characterization of heparan sulfate-proteoglycan of glomerular basement membranes.

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Abstract
Native and de novo synthesized heparan sulfate-proteoglycan (HS-PG) of basement membranes from isolated whole glomeruli [from rats] were characterized. Sepharose CL-6B chromatograms of [35S]sulfate-labeled de novo synthesized HS-PG extracted from whole glomeruli indicated identical MW characteristics to that isolated from purified basement membranes (Mr [molecular ratio] of intact HS-PG .apprxeq. 130,000; Mr of chains .apprxeq. 25,000). EM autoradiography showed that almost all radioactive grains were localized to the basement membranes proper. The estimated Mr of core protein .apprxeq. 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.