Bonser A M, Garcia-Webb P, Bhagat C I
Biochim Biophys Acta. 1983 Jun 2;762(3):390-7. doi: 10.1016/0167-4889(83)90003-4.
Previous studies have suggested that transglutaminase has a role in the internalization of some polypeptide hormones and is inhibited by the antibiotic, bacitracin. Bacitracin has been used in insulin-receptor studies to inhibit extracellular degradation of 125I-labelled insulin. The aim of this study was to investigate bacitracin's effect on 125I-labelled insulin-receptor interactions in isolated rat hepatocytes. 1 g/l bacitracin increased cell-associated 125I-labelled insulin insulin at 20, 30 and 37 degrees C (P less than 0.001, 0.0005 and 0.0005, respectively). At 5 and 15 degrees C (internalization does not occur), bacitracin did not affect cell-associated 125I-labelled insulin. The bacitracin effect was concentration dependent, increasing to 2 g/l. Scatchard analysis showed that bacitracin did not alter insulin receptor affinity or number. 1 g/l bacitracin abolished the effect of chloroquine. The increased cell-associated radioactivity with bacitracin was surface-bound in nature. 0.5 g/l bacitracin decreased 125I-labelled insulin degradation in hepatocyte suspensions (P less than 0.001) and in buffer previously incubated with hepatocytes (P less than 0.0005). More 125I-labelled insulin remained associated with cells during dissociation studies at 37 degrees C when the buffer contained 1 g/l bacitracin. Label that appeared in the buffer after 60 min was significantly more intact in the presence of bacitracin (P less than 0.025). These results suggest that bacitracin retards the internalization of 125I-labelled insulin in isolated rat hepatocytes.
先前的研究表明，转谷氨酰胺酶在某些多肽激素的内化过程中起作用，并且会被抗生素杆菌肽抑制。杆菌肽已被用于胰岛素受体研究中，以抑制125I标记胰岛素的细胞外降解。本研究的目的是调查杆菌肽对分离的大鼠肝细胞中125I标记胰岛素-受体相互作用的影响。1 g/l的杆菌肽在20、30和37摄氏度时增加了细胞相关的125I标记胰岛素（分别为P<0.001、0.0005和0.0005）。在5和15摄氏度（内化不发生）时，杆菌肽不影响细胞相关的125I标记胰岛素。杆菌肽的作用呈浓度依赖性，增加到2 g/l时仍有作用。Scatchard分析表明，杆菌肽不会改变胰岛素受体的亲和力或数量。1 g/l的杆菌肽消除了氯喹的作用。杆菌肽使细胞相关放射性增加的本质是表面结合。0.5 g/l的杆菌肽降低了肝细胞悬液中125I标记胰岛素的降解（P<0.001）以及先前与肝细胞孵育的缓冲液中125I标记胰岛素的降解（P<0.0005）。在37摄氏度的解离研究中，当缓冲液中含有1 g/l杆菌肽时，更多的125I标记胰岛素与细胞保持结合。在杆菌肽存在的情况下，60分钟后出现在缓冲液中的标记物明显更完整（P<0.025）。这些结果表明，杆菌肽可延缓分离的大鼠肝细胞中125I标记胰岛素的内化。
