Malbon C C
Biochim Biophys Acta. 1982 Feb 25;714(3):429-34. doi: 10.1016/0304-4165(82)90150-7.
Incubating rat fat cell membranes with [32P]NAD+ and cholera toxin results in ADP-ribosylation of three distinct components with approximate molecular weights of 42,000, 46,000 and 48,000. Partial proteolytic peptide maps of the Mr = 46,000 and 48,000 toxin-specific substrates generated by elastase, alpha-chymotrypsin, or Staphylococcus aureus V-8 protease were nearly identical, while those of the Mr = 42,000 target lacked several peptides common to both of the larger molecular weight targets. In addition, peptide maps generated from the Mr = 42,000 target displayed a number of peptides which were absent from the maps generated from either the Mr = 46,000 or 48,000 targets. These data suggest that the Mr = 46,000 and 48,000 substrates are closely related proteins, however the relationship between the Mr = 42,000 toxin-specific substrate and the larger peptides remains to be established. The relative patterns of fat cell membrane labelling by cholera toxin in the presence of [32P]NAD+ were identical in hypothyroid as compared to euthyroid rat fat cells.
用[32P]NAD+和霍乱毒素孵育大鼠脂肪细胞膜，会导致三种不同成分发生ADP-核糖基化，其分子量约为42,000、46,000和48,000。由弹性蛋白酶、α-胰凝乳蛋白酶或金黄色葡萄球菌V-8蛋白酶产生的分子量为46,000和48,000的毒素特异性底物的部分蛋白水解肽图谱几乎相同，而分子量为42,000的靶标的肽图谱则缺少几个较大分子量靶标共有的肽段。此外，分子量为42,000的靶标产生的肽图谱显示出一些在分子量为46,000或48,000的靶标产生的图谱中不存在的肽段。这些数据表明，分子量为46,000和48,000的底物是密切相关的蛋白质，然而，分子量为42,000的毒素特异性底物与较大肽段之间的关系仍有待确定。与甲状腺功能正常的大鼠脂肪细胞相比，甲状腺功能减退的大鼠脂肪细胞在[32P]NAD+存在下霍乱毒素对脂肪细胞膜的标记相对模式是相同的。
