Amyloid Precursor Protein

Alzheimer’s disease (AD) was first reported by A. Alzheimer, a German neuropathologist in 1907 and is considered as a major factor of dementia.

Amyloid β (Aβ, a major constituent of senile plaque) is cleaved from Amyloid Precursor Protein (APP; which exists in three main isoforms, APP695, APP751, and APP770) by β-secretase and subsequent γ-secretase.

The production of soluble APPβ (sAPPβ) by β-secretase cleavage corresponds to Aβ production. It is reported that APP gene mutation exists in individuals who suffer early-onset familial Alzheimer’s disease. Swedish mutation, one of the APP gene mutations, is a double mutation at positions -1 to -2 from the β-secretase cleavage site (Lys670->Asn and Met671->Leu). It is reported that Swedish mutation elevates Aβ40 and Aβ42 production, and that the mutation is utilized in establishment of transgenic mice.

It is considered that in the normal metabolic pathway, APP is first cleaved by α-secretase to produce soluble APPα (sAPPα) and subsequently P3 is cleaved from the remaining C-terminal fragment by γ-secretase. Other reports show βCTF (β-secretase C-terminal fragment) are cleaved by β-secretase but not by γ-secretase.

Accumulation of Aβ has been observed on cerebrovascular walls of nearly 90% of individuals suffering with AD. Aβ molecules, which accumulate in brain parenchyma, are mainly produced from APP expressed in neurons, APP695. In contrast, isoform APP770 was found to be expressed in cerebrovascular endothelial cells. It has been reported that Aβ produced from APP770 can accumulate on cerebrovascular walls.

ELISA kits for APP

Human sAPP, Total (highly sensitive) Assay Kit
Human sAPPβ-w (highly sensitive) Assay Kit
Human sAPPβ-sw (highly sensitive) Assay Kit
Human sAPPα (highly sensitive) Assay Kit
Human APP770 Assay Kit
Human APP βCTF Assay Kit

Mouse sAPPβ-w Assay Kit
Mouse/Rat sAPPα (highly sensitive) Assay Kit