Bradbury J M, Campbell R S, Thompson R J
Biochem J. 1984 Jul 15;221(2):351-9. doi: 10.1042/bj2210351.
Cyclic AMP-stimulated phosphorylation of membrane proteins in central-nervous-system myelin was investigated, with rabbit brain myelin. Subfractionation of a myelin membrane preparation by sucrose-density-gradient centrifugation produced a rapidly sedimenting population of membrane vesicles containing 5'-nucleotidase and acetylcholinesterase, a light membrane fraction containing myelin basic protein and 2',3'-cyclic nucleotide 3'-phosphodiesterase, and an intermediate membrane fraction containing the highest specific activity of 2',3'-cyclic nucleotide 3'-phosphodiesterase and a small proportion of myelin basic protein. Cyclic AMP stimulation of protein phosphorylation was confined to a protein of Mr 49 700, which co-electrophoresed with the upper component of the Wolfgram protein doublet. Cyclic AMP did not affect the phosphorylation of myelin basic protein. Cyclic AMP-stimulated phosphorylation of this protein followed 2',3'-cyclic nucleotide 3'-phosphodiesterase activity on subcellular fractionation and was correspondingly high in the intermediate or 'myelin-like' fraction on sucrose-density-gradient centrifugation.
利用兔脑髓磷脂对中枢神经系统髓磷脂中膜蛋白的环磷酸腺苷（cAMP）刺激的磷酸化作用进行了研究。通过蔗糖密度梯度离心对髓磷脂膜制剂进行亚分级分离，产生了一个快速沉降的膜泡群体，其中含有5'-核苷酸酶和乙酰胆碱酯酶；一个轻膜级分，含有髓磷脂碱性蛋白和2',3'-环核苷酸3'-磷酸二酯酶；以及一个中间膜级分，其含有最高比活性的2',3'-环核苷酸3'-磷酸二酯酶和一小部分髓磷脂碱性蛋白。cAMP对蛋白磷酸化的刺激作用仅限于分子量为49700的一种蛋白，该蛋白与沃尔夫拉姆蛋白双峰的上部成分共电泳。cAMP不影响髓磷脂碱性蛋白的磷酸化。该蛋白的cAMP刺激的磷酸化作用在亚细胞分级分离中与2',3'-环核苷酸3'-磷酸二酯酶活性一致，并且在蔗糖密度梯度离心的中间或“类髓磷脂”级分中相应较高。
