早老蛋白氨基端与羧基端结构域的相互作用

Interactions between Domains within the NH2- and COOH- terminalFragments of Presenilins

目的研究早老蛋白分子相互作用及相互作用结构域。方法利用 RT- PCR扩增人早老蛋白- 1和早老蛋白- 2全长 cDNA。在此基础上构建多种缺失体，采用酵母双杂交体系分析它们之间的相互作用。结果 (1）早老蛋白- 1的氨基端多肽与羧基端多肽之间存在直接的相互作用，能形成同源二（多）聚体。早老蛋白- 1羧基端相互作用位点定位于第 361～ 447位氨基酸。这一相互作用不依赖于其旁侧亲水环结构功能域的存在，也无需其它配体参与；（ 2）早老蛋白- 1氨基端片段或羧基端片段自身之间均不能形成同源二（多）聚体；（ 3）早老蛋白- 2氨基端多肽与羧基端多肽之间也存在上述相互作用，能形成同源二（多）聚体；（ 4）早老蛋白- 1的羧基端片段与早老蛋白- 2的氨基端片段、早老蛋白- 2的羧基端片段与早老蛋白- 1的氨基端片段不发生相互作用。结论早老蛋白氨基端多肽与羧基端多肽之间直接的相互作用可能参与、并有助于早老蛋白的装配和成熟，是其功能的结构基础。

To analyze the interactions between domains within the NH2- and COOH- terminal regions of presenilins. Methods The various constructions corresponding to NH2- terminal fragment (NTF) and COOH- terminal fragment (CTF) derivatives of presenilin 1 (PS1) and presenilin 2 (PS2) were generated by RT- PCR, and their interactions were assayed by yeast two- hybrid system. Results Domains within the NH- and COOH- terminal fragments of presenilins could directly interact with each other, and therefore form high molecular weight complex. The interaction site between domains within PS1 located at amino acid 361～ 447 of PS1 CTF, without the involvement of other partners. Similar interaction was not observed between PS11～ 360 and PS2341～ 448, PS21～ 340 and PS1361～ 467. Conclusions Intramolecular interaction between domains within the NH2- and COOH- terminal regions of presenilins may be critical to the folding and assembly of mature PS molecules.