Matthieu J M, Waehneldt T V
Brain Res. 1978 Jul 14;150(2):307-18. doi: 10.1016/0006-8993(78)90282-2.
The protein, glycoprotein and enzyme composition of myelin and myelin-related fraction (SN 4) from rat forebrain was compared with that of microsomal fractions. Acetylcholinesterase was largely confined to the microsomal fractions, wheras 2',3'-cyclic nucleotide-3'-phosphohydrolase (CNP) showed a high specific activity in myelin and SN 4 fractions. Nevertheless, the total specific activities of CNP present in microsomal membranes and in a water-soluble form were not negligible, and suggest that this enzyme has a wide distribution among subcellular particles. A high molecular weight protein was identified in myelin and all the other fractions studied. This protein (X), which co-migrates with the major myelin glycoprotein, was present in myelin and in fractions lacking typical myelin components as well as in fractions from a myelin deficient mutant, the Jimpy mouse. The results suggest that the X protein is probably a contaminant in isolated myelin, although the occurrence of this protein as an intrinsic component of several different membranes cannot be ruled out. Despite substantial overlap in density upon zonal centrifugation between SN 4 and microsomal fractions, the enzyme patterns of the fractions were different.
将大鼠前脑的髓磷脂和髓磷脂相关组分（SN 4）的蛋白质、糖蛋白和酶组成与微粒体组分进行了比较。乙酰胆碱酯酶主要存在于微粒体组分中，而2',3'-环核苷酸-3'-磷酸水解酶（CNP）在髓磷脂和SN 4组分中具有较高的比活性。然而，微粒体膜中以水溶性形式存在的CNP的总比活性也不可忽视，这表明该酶在亚细胞颗粒中分布广泛。在髓磷脂和所有其他研究的组分中鉴定出一种高分子量蛋白质。这种蛋白质（X）与主要的髓磷脂糖蛋白一起迁移，存在于髓磷脂中、缺乏典型髓磷脂成分的组分中以及来自髓磷脂缺陷突变体Jimpy小鼠的组分中。结果表明，X蛋白可能是分离的髓磷脂中的污染物，尽管不能排除该蛋白作为几种不同膜的固有成分存在的可能性。尽管在区带离心时SN 4和微粒体组分之间的密度有很大重叠，但各组分的酶谱不同。
