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The Biosynthesis of Glycoproteins

VI. Production of Extracellular Radioactive Macromolecules by Ehrlich Ascites Carcinoma Cells during Incubation with Glucosamine-¹⁴C¹

Department of Biological Chemistry, University of Illinois, College of Medicine, Chicago, Illinois

The incorporation of glucosamine-¹⁴C by Ehrlich ascites tumor cells has been measured both in vivo and in vitro. A considerable amount of high molecular weight radioactive material appears outside of the cells under both conditions. The radioactive extracellular fluids were subjected to gel filtration and to chromatography on DEAE-cellulose (diethylaminoethyl cellulose) columns. These experiments demonstrated the presence of a number of labeled components differing in their affinity to DEAE-cellulose, in their molecular size, and also in the ratio of ¹⁴C present as glucosamine and as galactosamine. Digestion with Pronase caused a considerable reduction of molecular sizes of the extracellular radioactive molecules, demonstrating that glycoprotein-like molecules are present. The results suggested that a differential leakage of glycoproteins occurred both in vivo and in vitro.

¹ This work was supported by grants from the NIH (CY2951) and from the Armed Forces Epidemiological Board (MD2133).

² Career Development Awardee of USPHS.

³ Present address: State University of New York Department of Biochemistry, Buffalo, N. Y.

Received 5/ 3/65.