Secretion of the beta/A4 amyloid precursor protein. Identification of a cleavage site in cultured mammalian cells.
Alzheimer's disease, a progressive neurodegenerative disorder, affects greater than 10% of the population of individuals greater than 65 years of age. A principal neuropathological feature of this disease is the senile plaque, a fibrillar extracellular deposit primarily composed of a approximately 4-kDa peptide, beta/A4, derived from the amyloid precursor protein (APP). Studies in cultured cells have documented that APP matures through a constitutive secretory pathway and is cleaved at or near the cell surface to release a large ectodomain into the extracellular space. To define the APP cleavage site, we constructed a Chinese hamster ovary cell line, which constitutively overexpresses human APP-770, and analyzed the COOH termini of secreted APP-770-related molecules. Using plasma desorption mass spectrometry and chemical microsequencing, we document that an APP cleavage site in Chinese hamster ovary cells leading to secretion occurs immediately COOH-terminal to lysine residue 687, which lies adjacent to the hydrophobic membrane-spanning domain.
Wang
R
R
Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2181.
Meschia
J F
JF
Cotter
R J
RJ
Sisodia
S S
SS
D000595:Amino Acid Sequence; D016229:Amyloid beta-Peptides / Q000235:genetics / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor; D000818:Animals; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D006224:Cricetinae; D003470:Culture Media; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D003470:Culture Media; D011498:Protein Precursors