Read R J, Funkhouser J D
Biochim Biophys Acta. 1983 Jun 16;752(1):118-26. doi: 10.1016/0005-2760(83)90239-4.
The present report describes the purification and characterization of a non-specific phospholipid-transfer protein from rat lung. The protein is the major phospholipid-transfer protein in lung which transfers phosphatidylcholine. The transfer protein was purified 1200-fold, with a final yield of 3%. The activity of the protein was monitored by measuring the transfer of [14C]phosphatidylcholine from radioactively labeled liposomes to mitochondria. The purified proteins transfers phosphatidylcholine, phosphatidylinositol, phosphatidylserine and phosphatidylethanolamine from radioactively labeled microsomes to either mitochondria or liposomes. The transfer of each phospholipid is proportional to its content in the donor membrane. The protein was purified from a pH 5.1 supernatant preparation by fractionation on DEAE-cellulose, Sephadex G-75 and hydroxyapatite. The molecular weight of the purified protein was estimated as 35 000 by SDS-polyacrylamide gel electrophoresis. The amino acid analysis revealed a high content of glutamic acid (including glutamine) and glycine. The specificity of the purified protein for transfer of phospholipids suggests that it may be the phospholipid-transfer activity which is highly enriched in isolated type II alveolar cells of rat lung.
本报告描述了从大鼠肺中纯化和鉴定一种非特异性磷脂转移蛋白的过程。该蛋白是肺中主要的磷脂转移蛋白，可转移磷脂酰胆碱。该转移蛋白被纯化了1200倍，最终产率为3%。通过测量[14C]磷脂酰胆碱从放射性标记的脂质体转移到线粒体来监测该蛋白的活性。纯化后的蛋白可将放射性标记的微粒体中的磷脂酰胆碱、磷脂酰肌醇、磷脂酰丝氨酸和磷脂酰乙醇胺转移到线粒体或脂质体中。每种磷脂的转移与其在供体膜中的含量成正比。该蛋白通过在DEAE-纤维素、葡聚糖G-75和羟基磷灰石上分级分离，从pH 5.1的上清液制备物中纯化得到。通过SDS-聚丙烯酰胺凝胶电泳估计纯化蛋白的分子量为35000。氨基酸分析显示谷氨酸（包括谷氨酰胺）和甘氨酸的含量很高。纯化蛋白对磷脂转移的特异性表明，它可能是大鼠肺分离的II型肺泡细胞中高度富集的磷脂转移活性物质。
