Patzelt C
Department of Physiological Chemistry, University of Würzburg, FRG.
Diabetologia. 1988 Apr;31(4):241-6. doi: 10.1007/BF00290592.
The effect of cationic amino acids, i.e. L-arginine and L-lysine, on protein synthesis in isolated rat islets of Langerhans has been investigated. Except for prosomatostatin, the formation of islet proteins is strongly depressed by these amino acids. This effect can be demonstrated within a few minutes and is rapidly reversible. For proglucagon, efficient concentrations of arginine are in the range of 1 to 10 mmol/l. The sensitivity of proinsulin formation to arginine is glucose-dependent: at 2.5 mmol/l, inhibitory concentrations of arginine are 10-fold lower than in the case of proglucagon. High glucose (20 mmol/l) almost completely protects proinsulin synthesis from this inhibition. The proteolytic conversion steps in hormonal precursor processing are not influenced by cationic amino acids as studied in intact islets and in a cell-free translational system. It is concluded that arginine and lysine inhibit protein synthesis in islet cells at the translational level. The release of these amino acids by prohormone conversion may exert a feed-back control on proinsulin formation that is modulated by glucose.
研究了阳离子氨基酸，即L-精氨酸和L-赖氨酸对分离的大鼠胰岛中蛋白质合成的影响。除了前生长抑素外，这些氨基酸会强烈抑制胰岛蛋白质的形成。这种作用在几分钟内即可显现，且迅速可逆。对于前胰高血糖素，精氨酸的有效浓度范围为1至10 mmol/l。胰岛素原形成对精氨酸的敏感性取决于葡萄糖：在2.5 mmol/l时，精氨酸的抑制浓度比前胰高血糖素的情况低10倍。高葡萄糖（20 mmol/l）几乎完全保护胰岛素原合成免受这种抑制。在完整胰岛和无细胞翻译系统中研究发现，激素前体加工中的蛋白水解转化步骤不受阳离子氨基酸的影响。得出的结论是，精氨酸和赖氨酸在翻译水平上抑制胰岛细胞中的蛋白质合成。前激素转化释放的这些氨基酸可能对胰岛素原的形成发挥反馈控制作用，而这种作用受葡萄糖调节。
