RBP Biosynthesis Role of the Liver

RBP is biosynthesized in and secreted (into the plasma) by the liver. In patients with chronic liver disease, plasma RBP levels are decreased, and the extent of decrease from normal is correlated with the extent of hepatic parenchy- 

The synthesis and secretion of RBP has been observed and studied with isolated liver cells in culture in vitro. Detailed studies have been carried out with two differentiated rat hepatoma cell lines (Smith et al., 1978). The production of RBP by primary rat hepatocytes in culture in vitro has also been observed (unpublished studies from the author s laboratory). Finally, the specific in vitro synthesis of rat RBP using isolated messenger RNA from rat liver and the rabbit reticulocyte in vitro protein-synthesizing system has been demonstrated (Soprano et al., 1981). Taken together, these various studies clearly establish the liver, and specifically the hepatic parenchymal cell, as the locus of RBP synthesis. The molecular and cellular mechanisms that are involved in the processes of RBP synthesis and secretion by the liver and the factors that regulate these processes are discussed in detail below. While it is clear that the liver is the major site of RBP synthesis, there is no evidence as to whether or not the liver is the only site of RBP synthesis in the body. 

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