RETINOL-BINDING PROTEIN - TRANSPORT PROTEIN FOR VITAMIN A IN HUMAN PLASMA
RETINOL-BINDING PROTEIN - TRANSPORT PROTEIN FOR VITAMIN A IN HUMAN PLASMA
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DOI：
10.1172/jci105889
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发表时间：
1968-01-01
影响因子：
15.9
通讯作者：
GOODMAN, DS
中科院分区：
文献类型：
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作者：
KANAI, M;RAZ, A;GOODMAN, DS
维生素A在人体血浆中以视黄醇的形式与一种特殊的转运蛋白结合而循环。这种蛋白质不同于已知的低密度和高密度血浆脂蛋白，并且具有大于1.21的水合密度。为了研究这种蛋白质，志愿者静脉注射视黄醇-15-14C。1-3天后收集血浆，通过测定14 C和跟踪蛋白结合视黄醇的荧光来监测视黄醇结合蛋白（RBP）的纯化。经Cohn分级分离、SephadexG-200和DEAE-Sephadex柱层析、制备型聚丙烯酰胺凝胶电泳和SephadexG-100柱层析，得到RBP纯品。这些程序导致制备的RBP至少98%的纯度，并已被纯化超过1500倍。纯化的RBP在电泳上具有α 1迁移率，分子量约为21，000 - 22，000。似乎每个RBP分子都有一个视黄醇结合位点。RBP溶液具有荧光（视黄醇的特征），并具有紫外吸收光谱，峰位于330 mμ（由结合的视黄醇产生）和280 mμ。在纯化的RBP中不存在脂肪酸或脂肪酰基链。血浆中RBP的通常浓度为3-4 mg/100 ml。在血浆中，RBP显然作为一种复合物与另一种较大的蛋白质一起循环，该蛋白质在电泳上具有前白蛋白迁移率。RBP-前白蛋白复合物在Cohn分级分离过程中以及在Sephadex和DEAE-Sephadex柱上层析过程中保持完整。该复合物在凝胶电泳过程中解离，允许分离和随后纯化每个组分。通过将分离的RBP和前白蛋白的溶液混合在一起再次形成复合物。因此，血浆中的视黄醇转运似乎涉及脂质-蛋白（视黄醇-RBP）相互作用和蛋白-蛋白（RBP-前白蛋白）相互作用。图片
Vitamin A circulates in human plasma as retinol bound to a specific transport protein. This protein differs from the known low and high density plasma lipoproteins and has a hydrated density greater than 1.21. In order to study this protein, volunteers were injected intravenously with retinol-15-14C. Plasma was collected 1-3 days later, and the purification of retinol-binding protein (RBP) was monitored by assaying for14C and also by following the fluorescence of the protein-bound retinol. Purification of RBP was effected by the sequence: Cohn fractionation, chromatography on columns of Sephadex G-200 and diethylaminoethyl (DEAE)-Sephadex, preparative polyacrylamide gel electrophoresis, and finally chromatography on Sephadex G-100. These procedures resulted in a preparation of RBP which was at least 98% pure and which had been purified more than 1500-fold. Purified RBP has α1mobility on electrophoresis and has a molecular weight of approximately 21,000-22,000. There appears to be one binding site for retinol per molecule of RBP. Solutions of RBP are fluorescent (characteristic of retinol) and have ultraviolet absorption spectra with peaks at 330 mμ (resulting from the bound retinol) and at 280 mμ. There are no fatty acid or fatty acyl chains present in purified RBP. The usual concentration of RBP in plasma is of the order of 3-4 mg/100 ml. In plasma, RBP apparently circulates as a complex, together with another, larger protein with prealbumin mobility on electrophoresis. The RBP-prealbumin complex remains intact during Cohn fractionation and during chromatography on Sephadex and on DEAE-Sephadex columns. The complex dissociates during gel electrophoresis, permitting the isolation and subsequent purification of each of the components. The complex is again formed by mixing together solutions of the separated RBP and of prealbumin. Retinol transport in plasma thus appears to involve both a lipid-protein (retinol-RBP) interaction and a protein-protein (RBP-prealbumin) interaction.Images