Regoeczi E, Chindemi P A, Debanne M T, Prieels J P
Am J Physiol. 1985 Jan;248(1 Pt 1):G8-14. doi: 10.1152/ajpgi.1985.248.1.G8.
The hepatic uptake and degradation of human diferric 125I-lactoferrin by the liver of the intact rat were studied. After intravenous injection, the tracer was rapidly cleared by the liver, probably by adsorptive pinocytosis, as inferred from observations with a 3,470-fold dose range. Endocytosed lactoferrin was transferred, with a delay, from a light-density subcellular particle to an organelle that had a density similar to lysosomes. The loss of protein bound 125I from the liver was very slow (half-life 2.7 h), and its rate matched closely that of human asialotransferrin type 3. Lactoferrin was found to be a poor substrate for lysosomal hydrolases in vitro. Fucoidin effected the release of a portion of lactoferrin from the liver back into the plasma. By using this agent, indirect evidence was obtained suggesting that a fraction of lactoferrin is being repeatedly endo- and exocytosed (diacytosed) by the liver over prolonged periods of time. Fucosylation failed to impart lactoferrinlike properties on human asialotransferrin type 1, although the derivatized protein exhibited a less than or equal to 10-fold increase in affinity for the liver relative to the parent molecule.
研究了完整大鼠肝脏对人双铁125I-乳铁蛋白的摄取和降解。静脉注射后，示踪剂迅速被肝脏清除，从3470倍剂量范围的观察结果推断，可能是通过吸附性胞饮作用清除的。内吞的乳铁蛋白会延迟地从低密度亚细胞颗粒转移到密度与溶酶体相似的细胞器中。肝脏中与蛋白质结合的125I的损失非常缓慢（半衰期2.7小时），其速率与3型人去唾液酸转铁蛋白的速率密切匹配。乳铁蛋白在体外被发现是溶酶体水解酶的不良底物。岩藻依聚糖促使一部分乳铁蛋白从肝脏释放回血浆中。通过使用这种试剂，获得了间接证据，表明一部分乳铁蛋白在很长一段时间内被肝脏反复进行内吞和外排（双胞吞）。岩藻糖基化未能赋予1型人去唾液酸转铁蛋白类似乳铁蛋白的特性，尽管衍生化蛋白相对于亲本分子对肝脏的亲和力增加了不到或等于10倍。
