McArdle H J, Douglas A J, Morgan E H
Placenta. 1984 Mar-Apr;5(2):131-8. doi: 10.1016/s0143-4004(84)80056-9.
Microvillar vesicles have been isolated from rat placentae. The vesicles have been characterized with respect to their microscopic appearance, their capacity to accumulate amino acids, and their enzyme activities. Alkaline phosphatase activity in the vesicle fraction was threefold greater than in the homogenate, and cytochrome c reductase activity was decreased fourfold. The vesicles were used to characterize transferrin binding to the trophoblast membrane in vitro. Transferrin binding was specific (K alpha = 8 X 10(7) M-1), and could not be replaced by apotransferrin. Apotransferrin binding showed lower affinity than the diferric transferrin, and did not appear to saturate over the range 0 to 500 micrograms/ml.
已从大鼠胎盘分离出微绒毛小泡。这些小泡已根据其微观外观、积累氨基酸的能力以及酶活性进行了表征。小泡部分中的碱性磷酸酶活性比匀浆中的高两倍，而细胞色素c还原酶活性降低了四倍。这些小泡用于在体外表征转铁蛋白与滋养层细胞膜的结合。转铁蛋白结合具有特异性（Kα = 8×10⁷ M⁻¹），且不能被脱铁转铁蛋白替代。脱铁转铁蛋白结合的亲和力低于二价铁转铁蛋白，并且在0至500微克/毫升范围内似乎未达到饱和。
