Weinhold P A, Rounsifer M E, Williams S E, Brubaker P G, Feldman D A
J Biol Chem. 1984 Aug 25;259(16):10315-21.
Phosphatidylglycerol and oleic acid had differential effects on cytidylyltransferase activity in cytosol and microsomes. The low-molecular-weight cytidylyltransferase in cytosol was stimulated more by phosphatidylglycerol than by oleic acid, whereas microsomal activity was stimulated more by oleic acid than by phosphatidylglycerol. Microsomal activity was stimulated by several unsaturated fatty acids but was not stimulated by saturated fatty acids. Bovine serum albumin decreased cytidylyltransferase activity in microsomes in the presence or absence of oleic acid but did not alter the activity measured in the presence of phosphatidylglycerol. The addition of oleic acid to albumin/microsome mixtures in amounts exceeding the binding capacity of albumin lead to complete recovery of the oleic acid stimulation. The addition of oleic acid to postmitochondrial supernatants resulted in a translocation of cytidylyltransferase activity from cytosol to microsome. The magnitude of the shift was severalfold greater with fetal preparations than adult. The free fatty acid content of microsomes increased coincident with the translocation. Bovine serum albumin, added to postmitochondrial supernatants, caused a release of cytidylyltransferase from microsomes to cytosol and a corresponding decrease in microsomal free fatty acid content. The amount of cytidylyltransferase activity in microsomes increased shortly after birth. The increase was accompanied by an increase in free fatty acid content of the microsomes. The increase in cytidylyltransferase activity and free fatty acids which occurred in vivo following birth was nearly identical to that obtained by adding oleic acid to postmitochondrial supernatants from fetal lung. We conclude that free fatty acids may affect the intracellular activity of cytidylyltransferase by promoting the translocation of inactive cytosolic forms to microsomes as well as by stimulating microsomal bound activity.
磷脂酰甘油和油酸对胞质溶胶和微粒体中的胞苷酸转移酶活性有不同影响。胞质溶胶中低分子量的胞苷酸转移酶受磷脂酰甘油的刺激比受油酸的刺激更大，而微粒体活性受油酸的刺激比受磷脂酰甘油的刺激更大。微粒体活性受到几种不饱和脂肪酸的刺激，但不受饱和脂肪酸的刺激。在有或没有油酸存在的情况下，牛血清白蛋白都会降低微粒体中的胞苷酸转移酶活性，但不会改变在磷脂酰甘油存在下测得的活性。向白蛋白/微粒体混合物中添加超过白蛋白结合能力的油酸会导致油酸刺激作用完全恢复。向后线粒体上清液中添加油酸会导致胞苷酸转移酶活性从胞质溶胶转移到微粒体。胎儿制剂的转移幅度比成人大几倍。微粒体中游离脂肪酸含量的增加与转移同时发生。向后线粒体上清液中添加牛血清白蛋白会导致胞苷酸转移酶从微粒体释放到胞质溶胶中，同时微粒体游离脂肪酸含量相应降低。出生后不久，微粒体中胞苷酸转移酶活性的量会增加。这种增加伴随着微粒体游离脂肪酸含量的增加。出生后体内发生的胞苷酸转移酶活性和游离脂肪酸的增加与向胎儿肺的后线粒体上清液中添加油酸所获得的增加几乎相同。我们得出结论，游离脂肪酸可能通过促进无活性的胞质形式向微粒体的转移以及刺激微粒体结合活性来影响胞苷酸转移酶的细胞内活性。
