Soprano D R, Soprano K J, Goodman D S
J Lipid Res. 1986 Feb;27(2):166-71.
A retinol-binding protein (RBP) cDNA clone was used to examine the effect of retinol status on the level of RBP mRNA in the liver, and to explore whether extrahepatic tissues contain RBP mRNA. In the first series of experiments, poly(A+) RNA was isolated from the livers of normal, retinol-depleted, and retinol-repleted rats and the levels of RBP mRNA in these samples were determined by both Northern blot and RNA Dot blot analyses. The levels of RBP mRNA in liver were similar in all three groups of rats. These findings confirm and extend previous studies which showed that retinol did not alter the in vivo rate of RBP synthesis or the translatable levels of RBP mRNA. In a second series of experiments, the RBP cDNA clone was used to survey poly (A+) RNA isolated from 12 different rat tissues for RBP mRNA by Northern blot analysis. We found that, along with the liver, many extrahepatic tissues contained RBP mRNA. Kidney contained RBP mRNA at a level of 5-10% of that of the liver, and the lungs, spleen, brain, stomach, heart, and skeletal muscle contained 1-3% of that of the liver. Translation of kidney poly (A+) RNA in rabbit reticulocyte lysates and immunoprecipitation of the translation products with anti-RBP antiserum resulted in a protein band of the same size as liver preRBP. These data suggest that RBP is synthesized in many extrahepatic tissues. It is possible that this extra-hepatically synthesized RBP may function in the recycling of retinol from these tissues back to the liver or to other target organs.
一个视黄醇结合蛋白（RBP）cDNA克隆被用于检测视黄醇状态对肝脏中RBP mRNA水平的影响，并探究肝外组织是否含有RBP mRNA。在第一组实验中，从正常、视黄醇缺乏和视黄醇补充的大鼠肝脏中分离出多聚腺苷酸（poly(A+)）RNA，并通过Northern印迹和RNA斑点印迹分析来测定这些样本中RBP mRNA的水平。三组大鼠肝脏中的RBP mRNA水平相似。这些发现证实并扩展了先前的研究，即视黄醇不会改变RBP在体内的合成速率或RBP mRNA的可翻译水平。在第二组实验中，通过Northern印迹分析，使用RBP cDNA克隆来检测从12种不同大鼠组织中分离出的多聚腺苷酸（poly(A+)）RNA中是否存在RBP mRNA。我们发现，除肝脏外，许多肝外组织都含有RBP mRNA。肾脏中RBP mRNA的水平为肝脏的5%-10%，而肺、脾、脑、胃、心脏和骨骼肌中含有肝脏的1%-3%。兔网织红细胞裂解物中肾脏多聚腺苷酸（poly(A+)）RNA的翻译以及用抗RBP抗血清对翻译产物的免疫沉淀产生了一条与肝脏前RBP大小相同的蛋白带。这些数据表明RBP在许多肝外组织中合成。肝外合成的这种RBP有可能在视黄醇从这些组织循环回到肝脏或其他靶器官中发挥作用。
