Chapus C, Puigserver A, Kerfélec B
Centre de Biochimie et de Biologie Moléculaire du Centre National de la Recherche Scientifique, Marseille, France.
Biochimie. 1988 Sep;70(9):1143-51. doi: 10.1016/0300-9084(88)90179-4.
Up to now, a non-covalent ternary complex in which the pro-carboxypeptidase A (subunit I) is associated to two functionally different proteins (subunits II and III) has only been found in the pancreas of ruminant species. In the other species studied so far, the pro-carboxypeptidase A is secreted either as a monomer or as a binary association with a functionally different protein. Subunit I is the immediate precursor of carboxypeptidase A. Subunit II is a chymotrypsinogen of the C-type, involved, like subunit I, in the degradation of proteins and peptides. Although closely related to the pancreatic serine endopeptidases, subunit III appears to be devoid of any specific enzymatic activity. Information about the spatial organization of the subunits in the ternary complex has been deduced from the sequential dissociation of the complex. In contrast to the mechanism of activation of subunits I and II, which is independent of their aggregation state, the catalytic properties of the resulting enzymes are sensitive to their aggregation state. Moreover, the structural basis of inactivity of subunit III as well as the physiological role of the ternary complex are also discussed in this review.
到目前为止，一种非共价三元复合物（其中前羧肽酶A（亚基I）与两种功能不同的蛋白质（亚基II和III）相关联）仅在反刍动物的胰腺中被发现。在迄今为止研究的其他物种中，前羧肽酶A要么作为单体分泌，要么与功能不同的蛋白质形成二元复合物分泌。亚基I是羧肽酶A的直接前体。亚基II是C型胰凝乳蛋白酶原，与亚基I一样，参与蛋白质和肽的降解。虽然与胰腺丝氨酸内肽酶密切相关，但亚基III似乎没有任何特定的酶活性。关于三元复合物中亚基的空间组织的信息是从复合物的顺序解离推导出来的。与亚基I和II的激活机制不同，亚基I和II的激活机制与其聚集状态无关，所产生的酶的催化特性对其聚集状态敏感。此外，本综述还讨论了亚基III无活性的结构基础以及三元复合物的生理作用。
