Human beta-amyloid precursor protein (APP), the transmembrane precursor of the Alzheimer's disease beta-amyloid peptide, was expressed in the yeast Saccharomyces cerevisiae by fusion to prepro-alpha-factor. From analysis of protease-deficient yeast strains, the fusion protein underwent partial processing by Kex2 protease to generate full-length APP and a fraction of the molecules were degraded in the vacuole. A soluble APP ectodomain fragment bearing lumenal but not cytosolic epitopes was released into the media, indicating cleavage by a "membrane protein-solubilizing proteinase" or "secretase" activity. Yeast cells contained a C-terminal APP fragment that co-migrated with authentic C-terminal fragment derived from alpha-secretase cleavage of full-length APP in human cells. The N-terminal sequence of immunoaffinity purified C-terminal APP fragment from yeast was identical to that reported in mammalian and insect cells. These results demonstrate the existence of a secretase activity in yeast. Furthermore, this yeast secretase activity may be related to an APP processing activity present in metazoan cells.

• PMID: 7961704
• PubMed
• PubTator

Reference Type

Journal Article | Research Support, U.S. Gov't, P.H.S.

Authors

Zhang H, Komano H, Fuller RS, Gandy SE, Frail DE

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