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炭疽杆菌外毒素是三组分蛋白质 ,构成两种毒素。水肿因子 (EF)和致死因子 (LF)分别是腺苷环化酶和金属蛋白酶 ,保护性抗原 (PA)与细胞表面受体结合并将水肿因子或致死因子转移进细胞内发挥毒性作用。在哺乳动物细胞上己发现有两种受体 ,分别是肿瘤内皮标志 8基因编码的细胞表面蛋白ATR/TEM8和毛细血管形态发生基因 2编码的细胞表面蛋白CMG2。这两种受体蛋白的生理功能都不十分清楚 ,它们之间的氨基酸序列有很高的同源性 (4 0 %～ 6 0 % )。氨基酸序列主要分信号肽、细胞外主基、跨膜区、脑浆尾四个区 ,细胞外主基内含vonWillebrand因子A主基或称整合素插入主基 (VWA/I主基 ) ,VWA/I主基内有金属离子依赖性粘连位点 (MIDAS) ,是主基与PA蛋白质相互作用所必不可少的。这两种受体都有几种异构体 ,主要差异在于胞浆尾区的氨基酸长度不同。两种VWA/I主基都有封闭PA功能 ,阻止细胞中毒的作用 ,有望作为抗毒素治疗炭疽
Bacillus anthracis exotoxin is a three-component protein that makes up two toxins. Edema (EF) and lethal factor (LF) are adenylate cyclases and metalloproteases, respectively. Protective antigen (PA) binds to cell surface receptors and translocates edema or lethal factor into the cell to exert toxic effects. Two receptors have been found on mammalian cells, the cell surface protein ATR / TEM8 encoded by the tumor endothelial marker 8 gene and the cell surface protein CMG2 encoded by the capillary morphogenetic gene 2, respectively. The physiological functions of these two receptor proteins are not very clear, the amino acid sequence between them have very high homology (40% ~ 60%). The amino acid sequence is mainly composed of signal peptide, extracellular matrix, transmembrane region and cerebrospinal meiosis. The extracellular matrix contains von Willebrand factor A (VWA / I) and VWA / I host a metal ion-dependent adhesion sites (MIDAS), is the main base and PA protein interaction is essential. There are several isoforms of these two receptors, the main difference being the length of the amino acids in the cytoplasmic tail region. Both VWA / I host have closed PA function, to prevent the role of cell poisoning, is expected as an antitoxin treatment of anthrax