Ng W W, Catus R G, Miller R K
Placenta Suppl. 1981;3:145-59.
The accumulation of the large and hydrophilic IgG, TC II-B12 and B12 molecules is demonstrated for the first time in a human placental system which has metabolic and physiological functions. A trypsin-sensitive component is present in the human term placental uptake of TC II-B12, for which a placental membrane receptor has been previously identified; this component is absent for the accumulation of free B12, which has no known receptor. Analyses of the cytosol and incubation media indicate degradation, binding and release of TC II-B12 and B12 as TC II-B12, free B12 and TC I-like complexes. It is suggested that the human placental tissue slice be used for studies involving the binding, uptake and processing of macromolecules as exemplified by TC II-B12.
首次在具有代谢和生理功能的人胎盘系统中证实了大分子亲水性免疫球蛋白G、转钴胺素II-B12和维生素B12分子的积累。人足月胎盘摄取转钴胺素II-B12时存在一种对胰蛋白酶敏感的成分，此前已鉴定出其胎盘膜受体；而游离维生素B12的积累不存在这种成分，游离维生素B12没有已知受体。对细胞溶质和孵育培养基的分析表明，转钴胺素II-B12和维生素B12以转钴胺素II-B12、游离维生素B12和类转钴胺素I复合物的形式发生降解、结合和释放。建议将人胎盘组织切片用于涉及大分子结合、摄取和加工的研究，如转钴胺素II-B12所示例的那样。
