期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1992
卷号：89
期号：4
页码：1345-1349
DOI：10.1073/pnas.89.4.1345
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Altered proteolysis of the beta-amyloid precursor protein (beta APP) resulting in release of the approximately 40-residue amyloid beta-protein (A beta P) may be a seminal pathogenetic event in Alzheimer disease. Using region-specific beta APP antibodies, we searched for stable proteolytic intermediates containing the intact A beta P region in brain tissue. A 22-kDa beta APP fragment was selectively detected in microvessels purified from cerebral cortex and other brain regions. On immunoblots, the 22-kDa band is labeled by five distinct antisera to beta APP carboxyl-terminal peptides and by affinity-purified antibodies to the recombinant proteins beta APP444-592 and beta APP592-695, which flank the A beta P region. The protein is virtually undetectable in whole-brain homogenates or microvessel-free fractions of brain. The protein is extractable from microvessels in Triton X-100 and other detergents, indicating its membrane association. In comparison with cortical microvessels, microvessels purified from white matter, cerebellum, and nonneural tissues contain lower amounts of the 22-kDa protein. The protein is found in microvessels of both normal and Alzheimer disease brains and occurs in low amounts in microvessels from fresh bovine brain. The size and specific immunoreactivity of the 22-kDa protein indicate that it is a stable fragment of beta APP containing the intact A beta P. The occurrence of this potentially amyloidogenic intermediate in microvessels is consistent with a vascular or hematogenous origin for some A beta P deposits in Alzheimer disease.
