Fujita T, Kouchi H, Ichikawa T, Syõno K
Department of Pure and Applied Sciences, University of Tokyo, Japan.
Plant Cell Physiol. 1993 Jan;34(1):137-42.
We have isolated a cDNA clone, designated GTI, by screening a tobacco genetic tumor cDNA library with a tumor-specific "subtracted" cDNA probe. The cDNA contained the entire coding sequence for a 94-amino-acid polypeptide that exhibited significant homology to members of the proteinase inhibitor I family from tomato and potato. The predicted protein has a pre-sequence of 22 amino acids but lacks a pro-sequence, unlike genes for proteinase inhibitor I isolated to date. Furthermore, the protein encoded by GTI cDNA has a novel reactive site, having glutamine as the P1 reactive residue. These results suggest that the GTI protein is a novel member of the proteinase inhibitor I family. The mRNA for GTI accumulated at a high level but only transiently after the wounding of tobacco plants. Thus, it appears that the GTI protein has a function that is related to the protection of tissues against damage due to wounding.
我们通过用肿瘤特异性“消减”cDNA探针筛选烟草遗传肿瘤cDNA文库，分离出了一个名为GTI的cDNA克隆。该cDNA包含一个94个氨基酸多肽的完整编码序列，该多肽与来自番茄和马铃薯的蛋白酶抑制剂I家族成员具有显著同源性。预测的蛋白质有一个22个氨基酸的前导序列，但不像迄今为止分离出的蛋白酶抑制剂I基因那样有一个前肽序列。此外，GTI cDNA编码的蛋白质有一个新的反应位点，以谷氨酰胺作为P1反应残基。这些结果表明，GTI蛋白是蛋白酶抑制剂I家族的一个新成员。GTI的mRNA在烟草植株受伤后高水平积累，但只是短暂积累。因此，GTI蛋白似乎具有与保护组织免受创伤损伤相关的功能。
