Metabolism in rat and affinity chromatographic purification of bone sialoprotein secreted by metabolically labelled rat osteoblastic cells (UMR-106)

An osteoblastic, established cell line UMR-106 was shown to synthesize high levels of the bone-specific, bone sialoprotein (BSP). BSP could be radiolabelled to high specific activity by adding ³H-glucosamine and ³⁵S-sulfate to the UMR-106 cultures and was isolated to high purity using ion-exchange and affinity chromatography on immobilized serotonin. The radiolabelled BSP, partially purified by ion-exchange chromatography, was injected intravenously into a rat in order to study its tissue distribution and urinary clearance. About 43% of the total recovered radioactivity was excreted in the urine within 75 h and the remainder was widely distributed, with the liver, kidney, heart and pelt showing the highest concentrations. The use of established cell lines for the synthesis of radiolabelled glycoconjugates, in conjunction with rapid purification on affinity matrix, provides a useful approach for studying the metabolism of glycoconjugates in whole animals.