Retinol-binding protein (RBP) is the specific plasma carrier of retinol, encharged of the vitamin transport from the liver to target cells. Ligand binding influences the RBP affinity for transthyretin (TTR), a homotetrameric protein involved in the RBP/TTR circulating complex, and the secretion rate of RBP. In fact, in vitamin A deficiency, the RBP release from the hepatocytes dramatically decreases and the protein accumulates in the cells, until retinol is available again. The mechanism is still not clear and new cellular models are needed to understand in detail how the soluble RBP can be retained inside the cell. In fish, a vitamin A transport system similar to that of higher vertebrates is emerging, although with significant differences.

中文翻译：

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维生素A转运：用于研究RBP分泌的体外模型。

视黄醇结合蛋白（RBP）是视黄醇的特定血浆载体，负责维生素从肝脏到靶细胞的转运。配体的结合影响RBP对运甲状腺素蛋白（TTR）的亲和力，运甲状腺素蛋白（TTR）是参与RBP / TTR循环复合体的同型四聚体蛋白质，并影响RBP的分泌速率。实际上，在维生素A缺乏症中，肝细胞释放的RBP急剧减少，蛋白质在细胞中积累，直到再次获得视黄醇为止。该机制仍不清楚，需要新的细胞模型来详细了解如何将可溶性RBP保留在细胞内。在鱼类中，与高级脊椎动物相似的维生素A转运系统正在出现，尽管有显着差异。