Assembly of the γ-secretase complex involves early formation of an intermediate subcomplex of Aph-1 and nicastrin
Assembly of the γ-secretase complex involves early formation of an intermediate subcomplex of Aph-1 and nicastrin
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DOI：
10.1074/jbc.m303941200
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发表时间：
2003-09-26
影响因子：
4.8
通讯作者：
Selkoe, DJ
中科院分区：
文献类型：
--
作者：
LaVoie, MJ;Fraering, PC;Selkoe, DJ
γ -分泌酶复合物是一种不寻常的多聚体蛋白酶，负责多种1型跨膜蛋白的膜内切割，包括β -淀粉样蛋白前体蛋白和Notch。遗传和生化数据显示，这种蛋白酶由早老素异二聚体（nicastrin的高度糖基化形式）和最近发现的基因产物Aph-1和Pen-2组成。尽管目前的证据支持这样的观点，即早老素包括蛋白酶的活性位点，而其他三种成分是蛋白水解活性所需的活性复合物的成员，但这三种辅助因子的单独作用仍不清楚。在这里，我们证明内源性Aph-1与一种未成熟的nicastrin相互作用，在早老素和Pen-2加入之前，在γ -分泌酶复合物的早期组装中形成稳定的中间体。我们的数据表明1)通过nicastrin的稳定和糖基化，以及nicastrin与未成熟的γ -分泌酶复合物的支架化，Aph-1参与了γ -分泌酶组装的早期阶段，2)早老素和后来的Pen-2在成熟蛋白酶的形成过程中与该中间体结合。
The gamma-secretase complex is an unusual multimeric protease responsible for the intramembrane cleavage of a variety of type 1 transmembrane proteins, including the beta-amyloid precursor protein and Notch. Genetic and biochemical data have revealed that this protease consists of the presenilin heterodimer, a highly glycosylated form of nicastrin, and the recently identified gene products, Aph-1 and Pen-2. Whereas current evidence supports the notion that presenilin comprises the active site of the protease and that the other three components are members of the active complex required for proteolytic activity, the individual roles of the three co-factors remain unclear. Here, we demonstrate that endogenous Aph-1 interacts with an immature species of nicastrin, forming a stable intermediate early in the assembly of the gamma-secretase complex, prior to the addition of presenilin and Pen-2. Our data suggest 1) that Aph-1 is involved in the early stages of gamma-secretase assembly through the stabilization and perhaps glycosylation of nicastrin and by scaffolding nicastrin to the immature gamma-secretase complex, and 2) that presenilin, and later Pen-2, bind to this intermediate during the formation of the mature protease.