Abstract: Methods and assays for detecting ?-secretase (BACE-1) activity in body fluids or tissue extracts from individuals, particularly individuals who have Alzheimer's disease, are disclosed. A truncated form of BACE-1 was isolated that can be used as a biomarker for Alzheimer's disease.

Abstract: Provided are methods of identifying inhibitors of ?-secretase that employ modified ?-secretase substrates. The modified ?-secretase substrates have ?-secretase cleavage sites that are altered from wild type. The amino acid sequences of the altered ?-secretase cleavage sites contain different amino acids in at least one of the positions P2-P1-P1?-P2? of the ?-secretase cleavage site. Many of the modified ?-secretase substrates are more efficient substrates for ?-secretase than are corresponding substrates having wild-type sequences, that is, these modified substrates are more susceptible to enzymatic breakdown by ?-secretase. Recombinant polynucleotide molecules encoding the modified ?-secretase substrates are provided. Antibodies that recognize cleavage products of the modified ?-secretase substrates are provided. Stable cell lines expressing the modified ?-secretase substrates are provided. Transgenic animals expressing the modified ?-secretase substrates are provided.

Abstract: Provided are methods of identifying inhibitors of ?-secretase that employ modified ?-secretase substrates. The modified ?-secretase substrates have ?-secretase cleavage sites that are altered from wild type. The amino acid sequences of the altered ?-secretase cleavage sites contain different amino acids in at least one of the positions P2-P1-P1?-P2? of the ?-secretase cleavage site. Many of the modified ?-secretase substrates are more efficient substrates for ?-secretase than are corresponding substrates having wild-type sequences, that is, these modified substrates are more susceptible to enzymatic breakdown by ?-secretase. Recombinant polynucleotide molecules encoding the modified ?-secretase substrates are provided. Antibodies that recognize cleavage products of the modified ?-secretase substrates are provided. Stable cell lines expressing the modified ?-secretase substrates are provided. Transgenic animals expressing the modified ?-secretase substrates are provided.

Abstract: The present invention provides DNA constructs, genetically engineered host cells, and methods for identifying inhibitors of amyloid precursor protein (APP) processing. The methods provide for the convenient identification, in a single assay, of inhibitors of ?-secretase and ?-secretase as well as other forms of APP processing. The methods rely on fusion proteins of APP and transcription factors in which APP processing releases the transcription factors, allowing the transcription factors to activate transcription of a reporter gene. Inhibitors are identified as substances that block or diminish transcription factor release from the fusion protein, thereby causing a diminution of reporter gene readout.

Abstract: Provided are methods of identifying inhibitors of &bgr;-secretase that employ modified &bgr;-secretase substrates. The modified &bgr;-secretase substrates have &bgr;-secretase cleavage sites that are altered from wild type. The amino acid sequences of the altered &bgr;-secretase cleavage sites contain different amino acids in at least one of the positions P2-P1-P1′-P2′ of the &bgr;-secretase cleavage site. Many of the modified &bgr;-secretase substrates are more efficient substrates for &bgr;-secretase than are corresponding substrates having wild-type sequences, that is, these modified substrates are more susceptible to enzymatic breakdown by &bgr;-secretase. Recombinant polynucleotide molecules encoding the modified &bgr;-secretase substrates are provided. Antibodies that recognize cleavage products of the modified &bgr;-secretase substrates are provided. Stable cell lines expressing the modified &bgr;-secretase substrates are provided.