Högstorp H, Carlin G
Institute of Forensic Medicine, University of Uppsala, Sweden.
Thromb Res. 1988 Feb 1;49(3):307-18. doi: 10.1016/0049-3848(88)90311-8.
Biosynthesis, intracellular processing and secretion of alpha 2-antiplasmin (AP) were studied in primary cultures of rat hepatocytes by the pulse-chase technique. The experiments demonstrated that AP is present intracellularly as a 73 kD form and is secreted as a 79 kD form with affinity for human plasminogen kringles. Addition of human plasmin to the culture medium resulted in the formation of a 141 kD protein, probably a plasmin-AP complex, concomitantly with the disappearance of the 79 kD protein. The presence of tunicamycin, a blocker of N-linked glycosylation in the endoplasmic reticulum, during culture resulted in expression of a 63 kD form in medium and cell lysates. This latter form was unchanged after reduction and displayed affinity for human plasminogen kringles. The 79 kD form in the culture medium was resistant to treatment with endo-beta-N-acetylglucosaminidase-H while the intracellular 73 kD form was degraded to 63 kD, indicating glycosylation in the Golgi complex. It is concluded that rat AP is synthesized in a 63 kD form which is glycosylated in the endoplasmic reticulum to a 73 kD form; and that this in turn is trimmed and glycosylated further in the Golgi complex to the 79 kD form, which is secreted. The glycosylation is apparently not necessary for the secretion or for the affinity for human plasminogen kringles.
采用脉冲追踪技术在原代大鼠肝细胞培养物中研究了α2-抗纤溶酶（AP）的生物合成、细胞内加工及分泌过程。实验表明，AP在细胞内以73 kD的形式存在，分泌时则为79 kD的形式，且对人纤溶酶原kringle具有亲和力。向培养基中添加人纤溶酶会导致形成一种141 kD的蛋白质，可能是纤溶酶-AP复合物，同时79 kD的蛋白质消失。培养过程中加入衣霉素（一种内质网中N-连接糖基化的阻断剂）会导致培养基和细胞裂解物中出现63 kD的形式。还原后，后一种形式未发生变化，且对人纤溶酶原kringle具有亲和力。培养基中的79 kD形式对内切β-N-乙酰葡糖胺糖苷酶-H处理具有抗性，而细胞内的73 kD形式则降解为63 kD，这表明在高尔基体复合体中发生了糖基化。得出的结论是，大鼠AP以63 kD的形式合成，在内质网中糖基化为73 kD的形式；进而在高尔基体复合体中进一步修剪并糖基化为79 kD的形式，然后分泌出去。糖基化显然对于分泌或对人纤溶酶原kringle的亲和力并非必需。
