Studies of the composition of purified Torpedo californica acetylcholine receptor and of its subunits.
Studies of the composition of purified Torpedo californica acetylcholine receptor and of its subunits.
复制标题
研究纯化的加州鱼雷乙酰胆碱受体及其亚基的组成。
作者：
R. Vandlen;W. Wu;J. Eisenach;M. Raftery
在限制蛋白水解降解的条件下，来自加州鱼雷的去污剂溶解的纯化受体蛋白以单体和二聚体形式存在。纯化的受体复合物由表观分子量分别为 40 000、50 000、60 000 和 65 000 的四种不同的多肽亚基组成。各个多肽均已纯化，其氨基酸组成显示它们相对疏水。此外，完整受体复合物和各个多肽的碳水化合物组成也已确定。氨基酸分析为存在与磷酸丝氨酸色谱特性相似的组分提供了证据。在碱中用 CH3NH2 处理受体，这种条件对 β-酪蛋白中的 O-磷酸丝氨酸残基进行定量修饰，完全消除了温和酸水解后对应于磷酸丝氨酸的峰。我们得出结论，该受体含有每个分子大约七个残基的O-磷酸丝氨酸残基，并且这些残基存在于所有组成的多肽中。其他形式的 O-取代丝氨酸和苏氨酸也被证明存在，最有可能作为糖基化残基。
Under conditions that limit proteolytic degradation, the detergent-solubilized purified receptor protein from Torpedo californica exists in monomeric and dimeric forms. The purified receptor complex is composed of four different polypeptide subunits of apparent molecular weights 40 000, 50 000, 60 000, and 65 000. The individual polypeptides have been purified and their amino acid compositions have shown them to be relatively hydrophobic. In addition, the carbohydrate composition of the intact receptor complex and of the individual polypeptides has been determined. Amino acid analysis provided evidence for the occurrence of a component with chromatographic properties similar to those of phosphoserine. Treatment of receptor with CH3NH2 in base, a condition which provided quantitative modification of O-phosphoserine residues in beta-casein, completely eliminated the peak corresponding to phosphoserine following mild acid hydrolysis. We conclude that the receptor contains O-phosphoserine residues to the extent of approximately seven residues per molecule and these residues occur in all constituent polypeptides. Other forms of O-substituted serine and threonine were also shown to occur, most likely as glycosylated residues.