Renal tubular uptake of protein: effect of molecular charge.
Renal tubular uptake of protein: effect of molecular charge.
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肾小管摄取蛋白质：分子电荷的影响。
DOI：
10.1152/ajprenal.1983.244.4.f436
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Carone,FA
中科院分区：
文献类型：
--
作者：
Christensen,EI;Rennke,HG;Carone,FA
在大鼠中评估了蛋白质分子电荷对近端肾小管重吸收的影响。天然和两种阳离子化形式的白蛋白、天然和阴离子化溶菌酶以及天然和阴离子化细胞色素 c 用 125 I 进行碘化。将每种类型蛋白质的不同形式交替微量输注到体内近曲小管的同一部位。肾小管重吸收被确定为尿液中输注和回收的 TCA 可沉淀放射性量之间的差异。在低浓度白蛋白下，近端肾小管重吸收的阳离子化溶菌酶是阴离子化白蛋白的 5 倍，阳离子化的溶菌酶是阴离子化溶菌酶的 2.7 倍。在四种浓度中的两种浓度下，近端肾小管对阳离子细胞色素 c 的摄取超过阴离子细胞色素 c。阳离子细胞色素c的摄取超过阳离子溶菌酶；然而，溶菌酶两种蛋白质的天然阳离子和阴离子种类之间的摄取差异比细胞色素c大得多。数据显示，较高的等电点显着增强近端肾小管对白蛋白、溶菌酶和细胞色素c的重吸收，并且具有相似分子量和等电点的蛋白质不一定重吸收到相同程度。这表明，除了总分子电荷之外，蛋白质表面上的分子构型和/或电荷分布决定了管腔膜的蛋白质结合以及随后的近端小管的内吞作用。
The effect of molecular charge of proteins on proximal tubular reabsorption was evaluated in the rat. Native and two cationized forms of albumin, native and anionized lysozyme, and native and anionized cytochrome c were iodinated with 125I. The different forms of each type of protein were alternately microinfused into the same site of proximal convoluted tubules in vivo. Tubular reabsorption was determined as the difference between the amounts of TCA-precipitable radioactivity infused and recovered in the urine. At low concentration of albumin 5 times more cationized than anionic albumin and 2.7 times more cationic than anionized lysozyme were reabsorbed by the proximal tubule. At two of four concentrations, proximal tubular uptake of cationic cytochrome c exceeded that of anionized cytochrome c. Uptake of cationic cytochrome c exceeded that of cationic lysozyme; however, the difference in uptake between native cationic and anionized species of the two proteins was much greater for lysozyme than for cytochrome c. The data reveal that a higher isoelectric point significantly enhances proximal tubular reabsorption of albumin, lysozyme, and cytochrome c and that proteins with similar molecular weight and isoelectric point are not necessarily reabsorbed to the same degree. This suggests that in addition to total molecular charge the molecular configuration and/or distribution of electrical charges on teh protein surface determine protein binding by the luminal membrane and subsequent endocytosis by the proximal tubule.