Related Experiment Video
Updated: Aug 4, 2026
10:03
Screening for Amyloid Aggregation by Semi-Denaturing Detergent-Agarose Gel Electrophoresis
Published on: July 16, 2008
Characterization of beta-amyloid peptide precursor processing by the yeast Yap3 and Mkc7 proteases
1New York State Institute for Basic Research in Developmental Disabilities, Staten Island 10314, USA.
Biochimica Et Biophysica Acta
|December 31, 1997
Summary
Researchers identified two yeast proteases, Yap3 and Mkc7, as alpha-secretases responsible for processing amyloid precursor protein (APP). This finding advances understanding of Alzheimer's disease pathways and suggests new targets for therapeutic intervention.
Area of Science:
- Biochemistry and Molecular Biology
- Neuroscience
- Cell Biology
Background:
- Beta-amyloid peptide precursor (APP) processing by beta- and gamma-secretases generates amyloid-beta (Abeta) peptides implicated in Alzheimer's disease.
- Alpha-secretase cleaves APP within the Abeta sequence, preventing Abeta formation, but its identity has remained elusive.
- The yeast secretory system shares similarities with mammalian systems, making it a valuable model for identifying processing enzymes.
Purpose of the Study:
- To identify the alpha-secretases responsible for cleaving amyloid precursor protein (APP).
- To investigate the role of specific yeast proteases in APP processing.
- To explore the potential of GPI-linked aspartyl proteases as mammalian alpha-secretases.
Main Methods:
- Expressed APP in Saccharomyces cerevisiae (yeast) to study its processing.
- Utilized yeast mutants (sec1, sec7, sec17, sec18) to analyze transport-dependent processing.
- Investigated the effect of vacuole neutralization on alpha-secretase activity.
- Assessed the processing kinetics of APP chimeras and mutated APP forms.
- Examined the impact of gene deletions for Yap3 and Mkc7 proteases on alpha-secretase activity.
Main Results:
- Yeast enzymes processed APP with the specificity of alpha-secretases.
- APP processing occurred in mutants affecting later secretory pathways but not early ER-to-Golgi transport.
- Deletions of Yap3 and Mkc7 genes significantly reduced alpha-secretase activity, with a combined reduction of 86%.
- Yap3 and Mkc7 proteases demonstrated cleavage of wild-type and mutated APP forms, suggesting their role as alpha-secretases in the late Golgi.
Conclusions:
- Yap3 and Mkc7 proteases function as alpha-secretases in yeast, processing APP in the late Golgi.
- These findings identify specific enzymes responsible for non-amyloidogenic APP processing.
- Suggests that GPI-linked aspartyl proteases warrant investigation as candidate alpha-secretases in mammalian systems for Alzheimer's disease research.
More Related Videos
Related Concept Videos
03:03Amyloid 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...
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
02:18The Proteasome
Eukaryotic cells can degrade proteins through several pathways. One of the most important amongst these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
01:29Protein 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...
01:32Export of Misfolded Proteins out of the ER
After folding, the ER assesses the quality of secretory and membrane proteins. The correctly folded proteins are cleared by the calnexin cycle for transport to their final destination, while misfolded proteins are held back in the ER lumen. The ER chaperones attempt to unfold and refold the misfolded proteins but sometimes fail to achieve the correct native conformation. Such terminally misfolded proteins are then exported to the cytosol by ER-associated degradation or ERAD pathway for...
03:03Amyloid 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...
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
01:13The Proteasome
Eukaryotic cells can degrade proteins through several pathways. One of the most important among these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...