Lammi M, Pon C L, Gualerzi C O
FEBS Lett. 1987 May 4;215(1):115-21. doi: 10.1016/0014-5793(87)80124-2.
A short form of Escherichia coli translational initiation factor IF3, repeatedly found both in vivo and in vitro, lacking the positively charged N-terminal hexapeptide has been produced by mild trypsinization. The properties of this short form of IF3 have been studied. Compared to the long native form of the factor, the shortened IF3 displays a markedly decreased thermal stability and affinity for the 30 S ribosomal subunit, as well as a reduced biological activity in protein synthesis. Following the loss of the N-terminal hexapeptide, a second peptide bond (Lys-90-Val-91) becomes easily accessible to proteolytic attack suggesting that formation of the short IF3 may be the first step in the physiological degradation of the factor.
通过温和的胰蛋白酶处理产生了一种大肠杆菌翻译起始因子IF3的短形式，该短形式在体内和体外均反复被发现，缺少带正电荷的N端六肽。已对这种IF3短形式的特性进行了研究。与该因子的长天然形式相比，缩短后的IF3热稳定性和对30S核糖体亚基的亲和力显著降低，并且在蛋白质合成中的生物活性也降低。在失去N端六肽后，第二个肽键（Lys-90-Val-91）变得易于受到蛋白水解攻击，这表明短IF3的形成可能是该因子生理降解的第一步。
