BOVINE AORTA CONTAINS AT LEAST 2 RELATED FORMS OF HEPARAN-SULFATE PROTEOGLYCAN

1. The proteoglycan peak from anion exchange chromatography of an extr act of bovine aorta was digested with chondroitinase ABC. The residual heparan sulphate proteoglycans were further purified by chromatograph y on Sepharose CL4B and DEAE-Sephacel to yield two species, of high an d low charge density. 2. Higher molecular weight material had a higher proportion of high charge density proteoglycan, while the lower molec ular weight species had a higher proportion of low charge density hepa ran sulphate proteoglycan. 3. The two species shared epitopes as they both reacted with an antibody to heparan sulphate proteoglycan from bo vine glomerular basement membrane. 4. On electron microscopy, both hig h and low charge density proteoglycans were visualized as 'tadpole-lik e' molecules, which showed a tendency to aggregate via their globular heads. 5. Bovine aortic smooth muscle cells were cultured in the prese nce of [S-35]sulphate and [H-3]glucosamine. Proteoglycans were isolate d from medium and cell layer extract by the methods outlined above. 6. The major HSPG species isolated from medium were significantly larger than those from cell layer and displayed substantial heterogeneity in both size of HS chain after papain digestion and size of protein core after heparitinase digestion. 7. The major cel layer species yielded two HS species of widely differing mel. wt after papain digestion, and a very small protein core after heparitinase digestion. Therefore cel l layer-associated HSPGs show a good deal more homogeneity than those found in the medium. 8. Further ion-exchange chromatography after dige stion with chondroitinase ABC revealed HSPG species of lower charge de nsity, possibly derived from a hybrid chondroitin sulphate-dermatan su lphate proteoglycan (CS/DSPG) after removal of the CS/DS chains.