Shen Q C, Simplaceanu V, Cottam P F, Wu J L, Hong J S, Ho C
Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213.
J Mol Biol. 1989 Dec 20;210(4):859-67. doi: 10.1016/0022-2836(89)90113-7.
The results of molecular genetic, biochemical and nuclear magnetic resonance studies on glutamine-binding protein of Escherichia coli suggest that the only two tryptophan residues, at positions 32 and 220, in the protein molecule are likely to be involved in (or sensitive to) interactions with the membrane-bound protein components of the glutamine transport system. It has been found that both tryptophan residues have limited motional freedom, are located away from the surface of the protein molecule and are not close to the ligand-binding site. Their presence, however, is required for the optimal transport of L-glutamine across the cytoplasmic membrane, though not essential for the ligand-binding process. The relevance of these results to the structure and function of the glutamine-binding protein in the glutamine transport system is discussed.
对大肠杆菌谷氨酰胺结合蛋白进行的分子遗传学、生物化学及核磁共振研究结果表明，该蛋白分子中仅有的两个色氨酸残基（位于第32位和第220位）可能参与了谷氨酰胺转运系统中与膜结合蛋白成分的相互作用（或对其敏感）。研究发现，这两个色氨酸残基的运动自由度有限，远离蛋白分子表面，且不靠近配体结合位点。然而，它们的存在对于L-谷氨酰胺跨细胞质膜的最佳转运是必需的，尽管对于配体结合过程并非必不可少。本文讨论了这些结果与谷氨酰胺转运系统中谷氨酰胺结合蛋白的结构和功能的相关性。
