Pen-2 is incorporated into the γ-secretase complex through binding to transmembrane domain 4 of presenilin 1
Pen-2 is incorporated into the γ-secretase complex through binding to transmembrane domain 4 of presenilin 1
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DOI：
10.1074/jbc.m509066200
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发表时间：
2005-12-23
影响因子：
4.8
通讯作者：
Iwatsubo, T
中科院分区：
文献类型：
--
作者：
Watanabe, N;Tomita, T;Iwatsubo, T
γ-分泌酶是一种多聚体膜蛋白复合物，由早老素 (PS)、尼卡斯特林 (Nct)、Aph-1 和 Pen-2 组成。它是一类非典型天冬氨酸蛋白酶的成员，可水解膜内的肽键。在γ-分泌酶复合物的生物合成过程中，Nct和Aph-1形成异二聚体中间复合物并与PS的C端区域结合，作为复合物的稳定支架。然后 Pen-2 被招募到该三聚体复合物中并触发 PS 的内切蛋白水解，从而赋予 γ 分泌酶活性。尽管 Pen-2 的积累取决于 PS，但γ-分泌酶复合物内 Pen-2 的结合伴侣仍然未知。我们通过表达一系列 PS1 突变体在 Psen1/Psen2 缺陷细胞中重建 PS1，其中 N 端六个跨膜结构域 (TMD) 之一被 CD4（I 型跨膜蛋白）或 CLAC-P（II 型跨膜蛋白）的结构域交换。我们报告说，PS1 的 TMD4 的近三分之二，包括保守的 Trp-Asn-Phe 序列，是其与 Pen-2 相互作用所必需的。使用包含PS1 TMD4的嵌合CD4分子，我们进一步证明PS1 TMD4具有与Pen-2的直接结合基序。 Pen-2 可能通过直接结合 PS1 的 TMD4 来激活 γ-分泌酶复合物。
gamma-Secretase is a multimeric membrane protein complex comprised of presenilin (PS), nicastrin (Nct), Aph-1, and Pen-2. It is a member of an atypical class of aspartic proteases that hydrolyzes peptide bonds within the membrane. During the biosynthetic process of the gamma-secretase complex, Nct and Aph-1 form a heterodimeric intermediate complex and bind to the C-terminal region of PS, serving as a stabilizing scaffold for the complex. Pen- 2 is then recruited into this trimeric complex and triggers endoproteolysis of PS, conferring gamma-secretase activity. Although the Pen- 2 accumulation depends on PS, the binding partner of Pen- 2 within the gamma-secretase complex remains unknown. We reconstituted PS1 in Psen1/Psen2 deficient cells by expressing a series of PS1 mutants in which one of the N-terminal six transmembrane domains (TMDs) was swapped with those of CD4 (a type I transmembrane protein) or CLAC-P (a type II transmembrane protein). We report that the proximal two-thirds of TMD4 of PS1, including the conserved Trp-Asn-Phe sequence, are required for its interaction with Pen-2. Using a chimeric CD4 molecule harboring PS1 TMD4, we further demonstrate that the PS1 TMD4 bears a direct binding motif to Pen-2. Pen-2 may contribute to the activation of the gamma-secretase complex by directly binding to the TMD4 of PS1.