Presenilin-1 and presenilin-2 exhibit distinct yet overlapping γ-secretase activities
Presenilin-1 and presenilin-2 exhibit distinct yet overlapping γ-secretase activities
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DOI：
10.1074/jbc.m300974200
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发表时间：
2003-06-20
影响因子：
4.8
通讯作者：
Li, YM
中科院分区：
文献类型：
--
作者：
Lai, MT;Chen, E;Li, YM
早老素-1（PS1）和早老素2（PS2）被认为是跨膜的乙酰化蛋白酶，其切割淀粉样前体蛋白和Notch。分别使用来自PS1（+/-）- PS2（-/-）和PS1（-/-）PS2（+/+）小鼠的囊胚衍生（BD）细胞和膜表征PS1和PS2介导的活性。通过使用通过体外转录和翻译产生的放射性标记的PS1和PS2标准品与标准曲线进行比较，由抗PS1和抗PS2免疫印迹信号的强度确定各种BD细胞中PS1和PS2的相对量。来自野生型、PS1（+/-）- PS2（-/-）和PS1（-/-）PS2（+/+）但不是PS1（-/-）PS2（-/-）BD细胞的细胞膜从C100 FLAG底物产生A β 40和A β 42产物。PS1相关的γ-分泌酶比PS2相关的γ-分泌酶显示出相当高的比活性。此外，与其他BD细胞和膜相比，PS1（+/-）- PS2（-/-）BD细胞和相应的膜表现出高得多的γ-分泌酶活性。PS1介导的γ-分泌酶活性与可被光活化活性定点γ-分泌酶抑制剂修饰的PS1的量而不是总PS1更好地相关;因此，野生型膜中只有一小部分（< 14%）的PS1似乎参与活性γ-分泌酶复合物。这一发现表明，PS1除了与其γ-分泌酶活性相关的功能外，还可能具有其他生物学功能。此外，PS1 γ-分泌酶复合物和PS2 γ-分泌酶复合物的活性可以根据它们对有效的γ-分泌酶抑制剂抑制的敏感性来区分。PS1 γ-分泌酶复合物和PS2 γ-分泌酶复合物的不同但重叠的酶性质意味着这两种推定的乙酰基类蛋白酶可能有助于不同的生物过程。
Presenilin- 1 ( PS1) and presenilin 2 ( PS2) are proposed to be transmembrane aspartyl proteases that cleave amyloid precursor protein and Notch. PS1- and PS2- mediated activities were individually characterized using blastocyst-derived ( BD) cells and membranes from PS1(+/-) - PS2(-/-) and PS1(-/-) PS2(+/+) mice, respectively. The relative amounts of PS1 and PS2 in the various BD cells were determined from the intensities of the anti- PS1 and anti-PS2 immunoblot signals by comparison with standard curves using radiolabeled PS1 and PS2 standards produced by in vitro transcription and translation. Cellular membranes from wild type, PS1(+/-) - PS2(-/-), and PS1(-/-)PS2(+/+) but not PS1(-/-) PS2(-/-) BD cells generated the Abeta40 and Abeta42 products from the C100FLAG substrate. PS1-associated gamma- secretase displays considerably higher specific activity than PS2- associated gamma- secretase. Moreover, the PS1(+/-) - PS2(-/-) BD cells and corresponding membranes exhibited much higher gamma- secretase activity as compared with other BD cells and membranes. The PS1- mediated gamma-secretase activity correlated better with the amount of PS1 that is modifiable by a photoactivated active site-directed gamma-secretase inhibitor rather than total PS1; hence, only a small portion (< 14%) of the PS1 in wild- type membranes appears to be engaged in an active γ-secretase complex. This finding suggests that PS1 may serve other biological functions in addition to that associated with its γ-secretase activity. Furthermore, the PS1 γ-secretase complex and the PS2 γ-secretase complex activities can be discriminated on the basis of their susceptibility to inhibition by a potent γ-secretase inhibitor. The distinct yet overlapping enzymatic properties of the PS1 γ-secretase complex and the PS2 γ-secretase complex imply that these two putative aspartyl class proteases may contribute to different biological processes.