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：1991
卷号：88
期号：22
页码：10307-10311
DOI：10.1073/pnas.88.22.10307
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Three alternatively spliced forms of the amyloid precursor protein (APP), APP-695, APP-751, and APP-770, were expressed in the baculovirus expression vector system. The recombinant proteins were secreted into the culture medium by infected insect cells, and APP molecules were detected in insect cells and medium 2 days after infection with the recombinant APP-baculoviruses. A partial sequence of the NH2 terminus of the secreted protein revealed identity with the native secreted protein and showed that the signal peptide was recognized and properly cleaved in insect cells. Purified secreted recombinant APP-751 comigrated with protease nexin 2 purified from platelets and fibroblasts. A 15-kDa COOH-terminal fragment of APP was also detected in cells infected with recombinant baculoviruses, suggesting that recombinant APP proteins were cleaved at the COOH-terminal end like native APP protein. Recombinant APP-751 and APP-770 formed complexes with epidermal growth factor-binding protein, whereas APP-695 did not. In addition, recombinant APP-751 and APP-770 inhibited trypsin and chymotrypsin activity, whereas APP-695 did not. Growth of a human fibroblast cell line, A-1, that required APP for complete growth, was restored upon addition of secreted recombinant APP-695 or APP-751. Thus, the appropriately sized, secreted recombinant APP proteins produced in this expression system are biologically active.
