Dutta-Roy A K, Gopalswamy N, Trulzsch D V
Eur J Biochem. 1987 Feb 2;162(3):615-9. doi: 10.1111/j.1432-1033.1987.tb10683.x.
Z protein or fatty-acid-binding protein is abundant in the cytosol of many cell types including liver cells. It is considered to play an important role in intracellular transport and metabolism of long-chain fatty acids and other organic anions. We studied the role of Z protein in the metabolism of prostaglandin E1 (PGE1). Binding of tritiated prostaglandin E1 to this fatty-acid-binding protein (Z protein) purified from rat liver was determined. The binding of [3H]prostaglandin E1 to Z protein is rapid, saturable and reversible. Scatchard analysis of [3H]PGE1 binding to Z protein showed a single class of binding sites with a dissociation constant (Kd) of 37 nM. The binding capacity is 110 nmol/mg Z protein. Optimal [3H]PGE1 binding occurred at pH 7.4. The presence of 3 mM MgCl2 stimulated the prostaglandin E1 binding to Z protein. Competition experiments show that the binding of this autacoid to Z protein is highly specific. It could not be displaced by other prostaglandins (PGA1, PGA2, PGE2, PGB1, PGI2, PGD2, PGF2 alpha, and 6-keto PGF1 alpha). Z protein might be involved in the metabolism of prostaglandins in the cytosol.
Z蛋白或脂肪酸结合蛋白在包括肝细胞在内的许多细胞类型的细胞质中含量丰富。它被认为在长链脂肪酸和其他有机阴离子的细胞内运输和代谢中起重要作用。我们研究了Z蛋白在前列腺素E1（PGE1）代谢中的作用。测定了氚标记的前列腺素E1与从大鼠肝脏中纯化的这种脂肪酸结合蛋白（Z蛋白）的结合情况。[3H]前列腺素E1与Z蛋白的结合迅速、可饱和且可逆。对[3H]PGE1与Z蛋白结合的Scatchard分析显示存在一类单一的结合位点，解离常数（Kd）为37 nM。结合容量为110 nmol/mg Z蛋白。最佳的[3H]PGE1结合发生在pH 7.4时。3 mM MgCl2的存在刺激了前列腺素E1与Z蛋白的结合。竞争实验表明，这种自分泌物质与Z蛋白的结合具有高度特异性。它不能被其他前列腺素（PGA1、PGA2、PGE2、PGB1、PGI2、PGD2、PGF2α和6-酮基PGF1α）取代。Z蛋白可能参与细胞质中前列腺素的代谢。
