Intracellular molecular species of human chorionic gonadotropin from normal but non-cultured first trimester placental tissues

Abstract

Intracellular forms of human chorionic gonadotropin (hCG) were analyzed by SDS-polyacrylamide gel electrophoresis, protein blotting and immunological techniques in normal but non-cultured first trimester placentae. Placental cells were found to contain the major components of the 23K and 19K forms of the beta-subunit and the 21K form of the alpha-subunit of hCG which remained sensitive to endoglycosidase H and Con A-Sepharose 4B and small amounts of mature (urinary) subunits. An unknown molecular species of the alpha-subunit (Mr=17K) that was not bound to Con A-Sepharose 4B was also detected. These intracellular molecular species accumulated in the placentae mainly during the first trimester. These results suggest that hCG subunits accumulate in placental cells as predominant intermediates containing high-mannose oligosaccharides.