Kato M, Kato K, Goodman D S
J Cell Biol. 1984 May;98(5):1696-704. doi: 10.1083/jcb.98.5.1696.
The immunocytochemical localization of cellular retinol-binding protein (CRBP), of plasma retinol-binding protein (RBP), and of plasma transthyretin (TTR) was studied in rat liver and kidney. The studies employed normal rats, retinol-deficient rats, and rats fed excess retinol. Antisera were prepared in rabbits against purified rat CRBP, RBP, and TTR. The primary antibodies and goat anti-rabbit IgG were purified by immunosorbent affinity chromatography, using the respective pure antigen coupled to Sepharose as the immunosorbent. This procedure effectively removed cross-reactive and heterophile antibodies, which permitted the specific staining and localization of each antigen by the unlabeled peroxidase-antiperoxidase method. CRBP was found to be localized in two cell types in the liver, the parenchymal cells and the fat-storing cells. Diffuse cytoplasmic staining for CRBP was seen in all the parenchymal cells. Much more intense staining for CRBP was seen in the fat-storing cells. The prominence of the CRBP-positive fat-storing cells changed markedly with vitamin A status. Thus, these cells were most prominent, and appeared most numerous, in liver from rats fed excess retinol. Both RBP and TTR were localized within liver parenchymal cells. The intensity of RBP staining increased markedly in retinol-deficient rat liver, consistent with previous biochemical observations. With the methods employed, specific staining for RBP or TTR was not seen in cells other than the parenchymal cells. In the kidney, all three proteins (CRBP, RBP, and TTR) were localized in the proximal convoluted tubules of the renal cortex. Staining for RBP was much more intense in normal kidney than in kidney from retinol-deficient rats. These findings reflect the fact that RBP in the tubules represents filtered and reabsorbed RBP. The pattern of specific staining for CRBP among the various tubules was very similar to that seen for RBP on adjacent, serial sections of kidney. The function of CRBP in the kidney is not known.
对大鼠肝脏和肾脏中细胞视黄醇结合蛋白（CRBP）、血浆视黄醇结合蛋白（RBP）以及血浆甲状腺素转运蛋白（TTR）进行了免疫细胞化学定位研究。研究采用了正常大鼠、维生素A缺乏大鼠以及摄入过量视黄醇的大鼠。用纯化的大鼠CRBP、RBP和TTR对兔制备抗血清。使用与琼脂糖偶联的各自纯抗原作为免疫吸附剂，通过免疫吸附亲和层析法纯化一抗和山羊抗兔IgG。该方法有效去除了交叉反应性抗体和嗜异性抗体，从而能够通过未标记的过氧化物酶-抗过氧化物酶法对每种抗原进行特异性染色和定位。发现CRBP定位于肝脏中的两种细胞类型，即实质细胞和贮脂细胞。在所有实质细胞中均可见CRBP的弥漫性胞质染色。在贮脂细胞中可见CRBP染色更强。CRBP阳性贮脂细胞的突出程度随维生素A状态而显著变化。因此，在摄入过量视黄醇的大鼠肝脏中，这些细胞最为突出且数量最多。RBP和TTR均定位于肝脏实质细胞内。在维生素A缺乏的大鼠肝脏中，RBP染色强度显著增加，这与先前的生化观察结果一致。采用这些方法，除实质细胞外，在其他细胞中未见到RBP或TTR的特异性染色。在肾脏中，所有三种蛋白质（CRBP、RBP和TTR）均定位于肾皮质的近端曲管。正常肾脏中RBP的染色比维生素A缺乏大鼠肾脏中的染色要强得多。这些发现反映了这样一个事实，即肾小管中的RBP代表滤过并重吸收的RBP。在肾脏相邻连续切片上，CRBP在不同肾小管中的特异性染色模式与RBP的非常相似。CRBP在肾脏中的功能尚不清楚。
