Related Experiment Video

Updated: Jul 13, 2026

Selection of Aptamers for Amyloid β-Protein, the Causative Agent of Alzheimer's Disease
15:23

Selection of Aptamers for Amyloid β-Protein, the Causative Agent of Alzheimer's Disease

Published on: May 14, 2010

Positive-negative epitope-tagging of beta amyloid precursor protein to identify inhibitors of A beta processing

D Seiffert1, T Mitchell, A M Stern

  • 1E400/3253, Department of Chemical Enzymology, DuPont Pharmaceuticals Company, 198880-0400, Wilmington, DE 19880-0400, USA. dietmar.a.sieffert@dupontpharma.com

Brain Research. Molecular Brain Research
|December 13, 2000
PubMed

In this report, a novel positive-negative epitope tagging approach was developed to study the cellular processing of beta amyloid precursor protein (beta APP). Amino acids centered around the alpha-secretase cleavage site within the A beta sequence were replaced with residues comprising an epitope for which high-affinity monoclonal antibodies are commercially available. The resulting mutant beta APP cDNAs were expressed in human embryonic kidney cells (HEK 293). Cleavage of labeled beta APP by beta- and gamma-secretase(s) results in the release of an epitope-tagged A beta peptide, whereas cleavage by alpha-secretase results in destruction of the epitope. Highly sensitive and specific immunoassays were developed to study processing of this labeled beta APP via the amyloidogenic pathway. Secretion of epitope-tagged A beta was prevented by MDL 28170, a previously described gamma-secretase inhibitor. Confocal microscopic studies revealed that processing and cellular trafficking of epitope-tagged beta APP was not different from wild-type beta APP. These results suggest that positive-negative epitope-tagged beta APP is normally processed within the cell and may be used to identify secretase inhibitors as therapeutics for Alzheimer's disease.

More Related Videos

Imaging the Intracellular Trafficking of APP with Photoactivatable GFP07:55

Imaging the Intracellular Trafficking of APP with Photoactivatable GFP

Published on: October 17, 2015

A11-positive β-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis06:17

A11-positive β-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis

Published on: May 22, 2018

Related Concept Videos

Amyloid Fibrils03:03

Amyloid Fibrils

Amyloid fibrils are aggregates of misfolded proteins.  Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils. 
Amyloid deposits were observed as early as 1639 in the liver and the spleen.   In 1854, Rudolph Virchow performed iodine staining, normally used to...
Protein Folding Quality Check in the RER01:29

Protein Folding Quality Check in the RER

ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...
Tagging and Fusion Proteins01:24

Tagging and Fusion Proteins

Proteins are involved in several cellular processes and biochemical reactions. Analyzing a specific protein of interest requires it to be isolated from the other proteins in the cell. This is achieved by overexpressing the specific gene in a suitable host to produce large quantities of the target protein. A tag or label is recombined with the gene to produce a fusion protein containing the target protein and the tag. The tags on these fusion proteins can then be used for easy detection and...