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Synthesis and Processing of Human Chorionic Gonadotropin Subunits in Cultured Choriocarcinoma Cells
Raymond W. Ruddon, Charlotte A. Hanson and Nancy J. Addison
Proceedings of the National Academy of Sciences of the United States of America
Vol. 76, No. 10 (Oct., 1979), pp. 5143-5147
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/70404
Page Count: 5
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Pulse and pulse-chase experiments have identified the presence of partially glycosylated precursors of the $\alpha $ and $\beta $ subunits of human chorionic gonadotropin (hCG) in cultured JAR choriocarcinoma cells. The $\alpha $ subunit precursor has an apparent molecular weight (by sodium dodecyl sulfate/polyacrylamide gel electrophoresis) of 18,000 (compared to 22,000 for fully processed $\alpha $ subunit); the $\beta $ subunit precursor has an apparent molecular weight of 24,000 (fully processed, 34,000). Both of these precursors appear to have an intracellular half-life of at least 1 hr and to contain the mannose core but not the terminal carbohydrate sequences. Fully processed $\alpha $ and $\beta $ subunits do not accumulate intracellularly, indicating that further processing of the precursors is followed by rapid secretion.
Proceedings of the National Academy of Sciences of the United States of America © 1979 National Academy of Sciences