Cell association and degradation of alpha 2-macroglobulin-trypsin complexes in hepatocytes and adipocytes.
Cell association and degradation of alpha 2-macroglobulin-trypsin complexes in hepatocytes and adipocytes.
复制标题
肝细胞和脂肪细胞中α2-巨球蛋白-胰蛋白酶复合物的细胞关联和降解。
DOI：
10.1016/0304-4165(83)90096-x
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
L. Sottrup
中科院分区：
文献类型：
--
作者：
J. Gliemann;Thomas R. Larsen;L. Sottrup
125 I标记的α2-巨球蛋白-泰普林复合物（125 I标记的α2-巨球蛋白·胰蛋白酶）与分离的大鼠脂肪细胞和肝细胞结合，在37°C下半衰期约为60 min。0.5 μg/ml ~（125）I标记的α2-巨球蛋白·胰蛋白酶的结合被未标记的α2-巨球蛋白·胰蛋白酶抑制，半抑制常数约为8 μg/ml（11 nM），~（125）I标记的α2-巨球蛋白在脂肪细胞中的结合程度较小（为α2-巨球蛋白·胰蛋白酶的10-40%），半抑制常数约为35 μg/ml。丹磺酰尸胺、杆菌肽、去Ca ~（2+）或胰蛋白酶预处理均能明显抑制~（125）I标记α-巨球蛋白·胰蛋白酶结合的细胞。用胰蛋白酶-EDTA处理细胞180分钟后，60%以上的细胞结合的~（125）I标记α2-巨球蛋白·胰蛋白酶未被清除，可能是内化的物质，~（125）I标记α2-巨球蛋白·胰蛋白酶被两种细胞悬液降解为三氯乙酸可溶性碎片，但在用这些细胞预孵育的孵育液中降解程度可忽略不计。0.5 μg/ml ~（125）I标记的α_2-巨球蛋白的降解率约为100%。~（125）I标记α2-巨球蛋白·胰蛋白酶的40%。高浓度（0.5mg/ml）和α2-巨球蛋白·胰蛋白酶可阻断~（125）I标记的α2-巨球蛋白·胰蛋白酶的降解。结论：α2-巨球蛋白·胰蛋白酶通过一种特异的饱和机制与脂肪细胞和肝细胞结合、内化和降解。
125I-labelledα2-macroglobulin-typrin complex (125I-labelledα2-macroglobulin·trypsin) was associated to isolated rat adipocytes and hepatocytes with a half-time of about 60 min at 37°C. The association of 0.5 μg/ml125I-labelledα2-macroglobulin·trypsin was inhibited by unlabelledα2-macroglobulin·trypsin with a half-inhibition constant of about 8 μg/ml (11 nM).125I-Labelledα2-macrioglubulin became cell-associated to a smaller extent (10–40% of that ofα2-macroglobulin·trypsin) and the half-inhibition constant was about 35 μg/ml in adipocytes. The cell associated of125I-labelledα-macroglobulin·trypsin was markedly inhibited by dansylcadaverin, bacitracin, omission of Ca2+from the medium or pretreatment of the cell with trypsin. After incubation for 180 min more than 60% of the cell-associated125-Ilabelledα2-macroglobulin·trypsin was not removed by treatment of the cells with trypsin-EDTA and represented probably internalized marterial.125I-Labelledα2-macroglobulin·trypsin was degraded to trichloroacetic acid-soluble fragments by suspensions of both cell types but only to a negligible extent by incubation media preincubated with these cells. The rate of degradation of 0.5 μg/ml125I-labelledα2-macroglobulin was approx. 40% of that of125I-labelledα2-macroglobulin·trypsin. Degradation of125I-labelledα2-macroglobulin·trypsin was abolished by a high concentration (0.5 mg/ml) andα2-macroglobulin·trypsin. It is concluded thatα2-macroglobulin·trypsin by a specific and saturable mechanism is bound to, internalized and degraded by isolated rat adipocytes and hepatocytes.