Amyloid beta A4 protein (IPR028866)

Short name: APP

Overlapping homologous superfamilies


Family relationships


Amyloid beta A4 protein (also known as APP or A4) consists of a large N-terminal extracellular region containing heparin-binding and copper-binding sites, a short hydrophobic transmembrane domain, and a short C-terminal intracellular domain. The N-terminal region is similar in structure to cysteine-rich growth factors and appears to function as a cell surface receptor, contributing to neurite growth, neuronal adhesion, axonogenesis and cell mobility [PMID: 16406235]. There are several alternative splicing isoforms of APP in humans. Two of the main isoforms, amyloid-beta40 (Abeta40) and amyloid-beta42 (Abeta42), are found prominently in the extracellular brain deposits associated with Alzheimer's disease (AD) [PMID: 24312636]. The ratio of Abeta42 to Abeta40 affects the pathogenesis of AD [PMID: 23442968].

APP can be processed by different sets of enzymes:

  • In the non-amyloidogenic (non-plaque-forming) pathway, APP is cleaved by alpha-secretase to yield a soluble N-terminal sAPP-alpha (neuroprotective) and a membrane-bound CTF-alpha. CTF-alpha is broken-down by presenilin-containing gamma-secretase to yield soluble p3 and membrane-bound AICD (nuclear signalling).
  • In the amyloidogenic pathway (plaque-forming), APP is broken down by beta-secretase to yield soluble sAPP-beta and membrane-bound CTF-beta. CTF-beta is broken down by gamma-secretase to yield soluble amyloid-beta and membrane-bound AICD. Amyloid-beta is required for neuronal function, but can aggregate to form amyloid plaques that seem to disrupt brain cells by clogging points of cell-cell contact.

GO terms

Biological Process

GO:0007399 nervous system development

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.