Processing of the amyloid protein precursor to potentially amyloidogenic derivatives

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Science  07 Feb 1992:
Vol. 255, Issue 5045, pp. 728-730
DOI: 10.1126/science.1738847


The approximately 120-kilodalton amyloid beta protein precursor (beta APP) is processed into a complex set of 8- to 12-kilodalton carboxyl-terminal derivatives that includes potentially amyloidogenic forms with the approximately 4-kilodalton amyloid beta protein (beta AP) at or near their amino terminus. In order to determine if these derivatives are processed in a secretory pathway or by the endosomal-lysosomal system, (i) deletion mutants that produce the normal set of carboxyl-terminal derivatives and shortened secreted derivatives were analyzed and (ii) the effect of inhibitors of endosomal-lysosomal processing was examined. In the secretory pathway, cleavage of the beta APP occurs at a single site within the beta AP to generate one secreted derivative and one nonamyloidogenic carboxyl-terminal fragment, whereas, in the endosomal-lysosomal system, a complex set of carboxyl-terminal derivatives is produced that includes the potentially amyloidogenic forms.

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