Amyloid-Precursor-Protein

• OMIM: 104760
• UniProt: P05067

The amyloid precursor protein ( amyloid precursor protein, APP) is an integral membrane protein from which it is assumed that in the formation of synapses is involved, although its function is not yet known exactly.

In the cleavage of APP, which has a size of 753-770 amino acid units by which alpha - secretases smaller, water-soluble proteins arise with 654-670 AS blocks, called SAPPS or APPsα that possess neuroprotective properties.

In the development of Alzheimer's disease cut two enzymes, beta -secretase and gamma -secretase, a 39 to 42 amino acids long, neurotoxic fragment of the amyloid precursor protein, which is called β -amyloid. This fragment is a major constituent of the plaques in the brains of Alzheimer's patients.

In humans, the gene for APP is located on chromosome 21 This is the reason that people with trisomy 21 (Down syndrome) often suffer from Alzheimer's disease at a young age. All animals have homologs. Mutations in the APP gene may familial ( genetic ) Alzheimer trigger.