[Endogenous lipid pattern, organ distribution and effect of diet on a fatty acid binding protein fraction of rat liver cytosol].

The endogenous lipid pattern of a fatty acid binding protein (FABP; synonym: "Z"-protein) in the cytosolic fraction of rat liver involves besides "free" fatty acids also phospholipids and mono-, di- and triacylglycerols. The relation between "free" fatty acids and the sum of all other lipids is nearly 1. In consequence of this result a correction of the idea is necessary that the FABP specifically binds only fatty acids. With immunological techniques it has been shown that the FABP has no organ-specificity and no immunological relation to the lipoproteins of the serum. A high content of fat in the diet (25% fat) compared with a low fat content of the diet (1% fat) led to an increase of the concentration of FABP in the cytosols of different rat organs (liver, intestinal mucosa, fat tissue and heart). Therefore a physiological function in the intracellular translocation of the fatty acids in different rat organs was inferred.