Presenilins are processed by caspase-type proteases.
Presenilin 1 ( PS1) and presenilin 2 ( PS2) are endoproteolytically processed in vivo and in cell transfectants to yield 27-35-kDa N-terminal and 15-24-kDa C-terminal fragments. We have studied the cleavage of PS1 and PS2 in transiently and stably transfected hamster kidney and mouse and human neuroblastoma cells by immunoblot and pulse-chase experiments. C-terminal fragments were isolated by affinity chromatography and SDS-polyacrylamide gel electrophoresis and sequenced. The processing sites identified in PS1 and PS2 (Asp345/Ser346 and Asp329/Ser330, respectively) are typical for caspase-type proteases. Specific caspase inhibitors and cleavage site mutations confirmed the involvement of caspase(s) in PS1 and PS2 processing in cell transfectants. Fluorescent peptide substrates carrying the PS-identified cleavage sites were hydrolyzed by proteolytic activity from mouse brain. The PS2-derived peptide substrate was also cleaved by recombinant human caspase-3. Additional processing of PS2 by non-caspase-type proteases was also observed.[1]References
- Presenilins are processed by caspase-type proteases. Loetscher, H., Deuschle, U., Brockhaus, M., Reinhardt, D., Nelboeck, P., Mous, J., Grünberg, J., Haass, C., Jacobsen, H. J. Biol. Chem. (1997) [Pubmed]
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