Department of Biology, Division of General Physiology, University of Oslo, Blindern, P.O. Box 1051, 0316, Oslo 3, Norway.
Fish Physiol Biochem. 1989 Nov;6(6):367-75. doi: 10.1007/BF01875606.
A mannose-terminated glycoprotein,(125)I-invertase, was taken up and degraded by isolated rainbow trout liver cells at 12°C. The uptake was inhibited by EGTA and no degradation occurred in the presence of ammonium ions. The liver cell suspension was fractionated by differential centrifugation in parenchymal and nonparenchymal cells, respectively. The parenchymal liver cells seemed to be the most active cells in uptake of labelled invertase bothin vitro andin vivo. Only negligible amounts of ligand were recovered in the nonparenchymal cells. Internalization of(125)I-invertase at different temperatures was demonstrated indirectly by releasing surface-bound ligand with EGTA. Ligand was internalized even at 0°C in trout liver cells.In vitro uptake of(125)I-invertase was inhibited by excess unlabelled invertase, by mannan and by N-acetylglucosamine.These data suggest that invertase is endocytosed by a mannose-specific pathway by the parenchymal liver cells of rainbow trout.
甘露糖末端糖蛋白（125）I-转化酶在 12°C 时被分离的虹鳟鱼肝细胞摄取并降解。摄取被 EGTA 抑制，并且在存在铵离子的情况下没有发生降解。肝细胞悬浮液通过差速离心分别在实质细胞和非实质细胞中进行分离。实质细胞似乎是摄取标记的转化酶的最活跃的细胞，无论是在体外还是在体内。非实质细胞中仅回收了微不足道的配体。通过用 EGTA 释放表面结合的配体，间接证明了（125）I-转化酶在不同温度下的内化。即使在 0°C 时，在虹鳟鱼肝细胞中也可以内化配体。（125）I-转化酶的体外摄取被过量的未标记的转化酶、甘露聚糖和 N-乙酰葡萄糖胺抑制。这些数据表明，转化酶被虹鳟鱼的实质细胞通过甘露糖特异性途径内吞。
