Familial Alzheimer's disease-associated mutations block translocation of full-length presenilin 1 to the nuclear envelope

A polyclonal antibody, M5, to the hydrophilic loop domain of human presenil in 1 (PS1) was prepared. Western blot and immunoprecipitation analyses show ed that M5 specifically recognized the processed C-terminal fragment, but n ot the full-length PS1. Epitope mapping analysis revealed that the essentia l sequence for recognition of the C-terminal fragment by M5 is DPEAQRR (302 -308). The recognition of the C-terminal fragment by M5 in a processing-dep endent manner was further confirmed by competitive enzyme-linked immunosorb ent assay using the synthetic peptide L281 (281-311), which contains the pu tative processing site and the preceding amino acids to the site. Although L281 contains the epitope sequence for M5, the maximum inhibition was only 14%. Immunocytochemistry using M5 combined with hL312, which recognizes bot h full-length PSI and the C-terminal fragment, allowed us to distinguish th e localization of the processed C-terminal fragment from that of full-lengt h PS1. Confocal microscopy demonstrated that the full-length form of wild-t ype PSI is preferentially located in the nuclear envelope, while the proces sed C-terminal fragment is mainly present in the endoplasmic reticulum (ER) . However, PS1 with familial Alzheimer's disease-associated mutations could not translocate to the nuclear envelope, and both the full-length and proc essed mutants were co-localized in the ER. (C) 2000 Elsevier Science Irelan d Ltd and the Japanese Neuroscience Society. All rights reserved.