1987 年 102 巻 5 号 p. 993-1001
To determine the subcellular sites for synthesis and processing of human chorionic gonadotropin subunits in cells, first trimester placental cells were fractionated sub-cellularly on sucrose density gradients. Analysis of the subcellular fractions by immunobinding techniques revealed that the rough endoplasmic reticulum-rich fraction contained only intermediates having high-mannose oligosaccharides, but the Golgi-rich fraction contained not only intermediates but also mature forms which were resistant toendoglycosidase H but sensitive to neuraminidase. These results show that humanchorionic gonadotropin subunits are synthesized in the rough endoplasmic reticulum as forms containing high-mannose oligosaccharides, and their maturation occurs in the Golgi apparatus by trimming with endogenous glycosidases. They are then modified by addition of complex oligosaccharides and terminal sialic acid through glycosyltransferases.