Amyloid-beta precursor protein

Homo sapiensTaxon: 9606

3D-structureAlternative splicingAlzheimer diseaseAmyloidAmyloidosisApoptosisCell adhesionCell membraneCell projectionCoated pitCopperCytoplasm+31

Longueur de Séquence

770

acides aminés

Poids Moléculaire

86.9 kDa

théorique

Structures Expérimentales

entrées PDB

Maladies Associées

enregistrées

Fonction

Functions as a cell surface receptor and performs physiological functions on the surface of neurons relevant to neurite growth, neuronal adhesion and axonogenesis. Interaction between APP molecules on neighboring cells promotes synaptogenesis (PubMed:25122912). Involved in cell mobility and transcription regulation through protein-protein interactions. Can promote transcription activation through binding to APBB1-KAT5 and inhibits Notch signaling through interaction with Numb. Couples to apoptosis-inducing pathways such as those mediated by G(o) and JIP. Inhibits G(o) alpha ATPase activity (By similarity). Acts as a kinesin I membrane receptor, mediating the axonal transport of beta-secretase and presenilin 1 (By similarity). By acting as a kinesin I membrane receptor, plays a role in axonal anterograde transport of cargo towards synapses in axons (PubMed:17062754, PubMed:23011729). Involved in copper homeostasis/oxidative stress through copper ion reduction. In vitro, copper-metallated APP induces neuronal death directly or is potentiated through Cu(2+)-mediated low-density lipoprotein oxidation. Can regulate neurite outgrowth through binding to components of the extracellular matrix such as heparin and collagen I and IV. The splice isoforms that contain the BPTI domain possess protease inhibitor activity. Induces a AGER-dependent pathway that involves activation of p38 MAPK, resulting in internalization of amyloid-beta peptide and leading to mitochondrial dysfunction in cultured cortical neurons. Provides Cu(2+) ions for GPC1 which are required for release of nitric oxide (NO) and subsequent degradation of the heparan sulfate chains on GPC1 Amyloid-beta peptides are lipophilic metal chelators with metal-reducing activity. Bind transient metals such as copper, zinc and iron. In vitro, can reduce Cu(2+) and Fe(3+) to Cu(+) and Fe(2+), respectively. Amyloid-beta peptides bind to lipoproteins and apolipoproteins E and J in the CSF and to HDL particles in plasma, inhibiting metal-catalyzed oxidation of lipoproteins. Promotes both tau aggregation and TPK II-mediated phosphorylation. Interaction with overexpressed HADH2 leads to oxidative stress and neurotoxicity. Also binds GPC1 in lipid rafts More effective reductant than amyloid-beta protein 40. May activate mononuclear phagocytes in the brain and elicit inflammatory responses Appicans elicit adhesion of neural cells to the extracellular matrix and may regulate neurite outgrowth in the brain The gamma-CTF peptides as well as the caspase-cleaved peptides, including C31, are potent enhancers of neuronal apoptosis

Localisation & Distribution

Spécificité Tissulaire

Expressed in the brain and in cerebrospinal fluid (at protein level) (PubMed:2649245). Expressed in all fetal tissues examined with highest levels in brain, kidney, heart and spleen. Weak expression in liver. In adult brain, highest expression found in the frontal lobe of the cortex and in the anterior perisylvian cortex-opercular gyri. Moderate expression in the cerebellar cortex, the posterior perisylvian cortex-opercular gyri and the temporal associated cortex. Weak expression found in the striate, extra-striate and motor cortices. Expressed in cerebrospinal fluid, and plasma. Isoform APP695 is the predominant form in neuronal tissue, isoform APP751 and isoform APP770 are widely expressed in non-neuronal cells. Isoform APP751 is the most abundant form in T-lymphocytes. Appican is expressed in astrocytes

Maladies Associées

Alzheimer disease 1

A form of Alzheimer disease, a neurodegenerative disorder characterized by progressive dementia, loss of cognitive abilities, and deposition of fibrillar amyloid proteins as intraneuronal neurofibrillary tangles, extracellular amyloid plaques and vascular amyloid deposits. The major constituents of these plaques are neurotoxic amyloid-beta protein 40 and amyloid-beta protein 42, that are produced by the proteolysis of the transmembrane APP protein. The cytotoxic C-terminal fragments (CTFs) and the caspase-cleaved products, such as C31, are also implicated in neuronal death. It can be associated with cerebral amyloid angiopathy. Alzheimer disease can be associated with cerebral amyloid angiopathy.

Cerebral amyloid angiopathy, APP-related

A hereditary localized amyloidosis due to amyloid-beta A4 peptide(s) deposition in the cerebral vessels. The principal clinical characteristics are recurrent cerebral and cerebellar hemorrhages, recurrent strokes, cerebral ischemia, cerebral infarction, and progressive mental deterioration. Patients develop cerebral hemorrhage because of the severe cerebral amyloid angiopathy. Parenchymal amyloid deposits are rare and largely in the form of pre-amyloid lesions or diffuse plaque-like structures. They are Congo red negative and lack the dense amyloid cores commonly present in Alzheimer disease. Some affected individuals manifest progressive aphasic dementia, leukoencephalopathy, and occipital calcifications.

Séquence d'Acides Aminés

MLPGLALLLLAAWTARALEVPTDGNAGLLAEPQIAMFCGRLNMHMNVQNGKWDSDPSGTK
TCIDTKEGILQYCQEVYPELQITNVVEANQPVTIQNWCKRGRKQCKTHPHFVIPYRCLVG
EFVSDALLVPDKCKFLHQERMDVCETHLHWHTVAKETCSEKSTNLHDYGMLLPCGIDKFR
GVEFVCCPLAEESDNVDSADAEEDDSDVWWGGADTDYADGSEDKVVEVAEEEEVAEVEEE

Format FASTA · 770 acides aminés · masse 86.9 kDa

Structures Expérimentales

50 entrées PDB

1AAP1AMB1AMC1AML1BA41BA61BJB1BJC1BRC1CA01HZ31IYT1MWP1OWT1QCM1QWP1QXC1QYT1TAW1TKN1X111Z0Q1ZE71ZE91ZJD2BEG2BP42FJZ2FK12FK22FK32FKL2FMA2G472IPU2LFM2LLM2LMN2LMO2LMP2LMQ2LNQ2LOH2LP12LZ32LZ42M4J2M9R2M9S2MGT

Modifications Post-Traductionnelles

•Proteolytically processed under normal cellular conditions. Cleavage either by alpha-secretase, beta-secretase or theta-secretase leads to generation and extracellular release of soluble APP peptides, S-APP-alpha and S-APP-beta, and the retention of corresponding membrane-anchored C-terminal fragments, C80, C83 and C99. Subsequent processing of C80 and C83 by gamma-secretase yields P3 peptides. This is the major secretory pathway and is non-amyloidogenic. Alternatively, presenilin/nicastrin-mediated gamma-secretase processing of C99 releases the amyloid-beta proteins, amyloid-beta protein 40 and amyloid-beta protein 42, major components of amyloid plaques, and the cytotoxic C-terminal fragments, gamma-CTF(50), gamma-CTF(57) and gamma-CTF(59). PSEN1 cleavage is more efficient with C83 than with C99 as substrate (in vitro) (PubMed:30630874). Amyloid-beta protein 40 and Amyloid-beta protein 42 are cleaved by ACE (PubMed:11604391, PubMed:16154999). Many other minor amyloid-beta peptides, amyloid-beta 1-X peptides, are found in cerebral spinal fluid (CSF) including the amyloid-beta X-15 peptides, produced from the cleavage by alpha-secretase and all terminating at Gln-686
•Proteolytically cleaved by caspases during neuronal apoptosis. Cleavage at Asp-739 by either CASP6, CASP8 or CASP9 results in the production of the neurotoxic C31 peptide and the increased production of amyloid-beta peptides
•N-glycosylated (PubMed:2900137). N- and O-glycosylated (PubMed:2649245). O-glycosylation on Ser and Thr residues with core 1 or possibly core 8 glycans. Partial tyrosine glycosylation (Tyr-681) is found on some minor, short amyloid-beta peptides (amyloid-beta 1-15, 1-16, 1-17, 1-18, 1-19 and 1-20) but not found on amyloid-beta protein 38, amyloid-beta protein 40 nor on amyloid-beta protein 42. Modification on a tyrosine is unusual and is more prevelant in AD patients. Glycans had Neu5AcHex(Neu5Ac)HexNAc-O-Tyr, Neu5AcNeu5AcHex(Neu5Ac)HexNAc-O-Tyr and O-AcNeu5AcNeu5AcHex(Neu5Ac)HexNAc-O-Tyr structures, where O-Ac is O-acetylation of Neu5Ac. Neu5AcNeu5Ac is most likely Neu5Ac 2,8Neu5Ac linked. O-glycosylations in the vicinity of the cleavage sites may influence the proteolytic processing. Appicans are L-APP isoforms with O-linked chondroitin sulfate
•Phosphorylation in the C-terminal on tyrosine, threonine and serine residues is neuron-specific (PubMed:10341243). Phosphorylation can affect APP processing, neuronal differentiation and interaction with other proteins (PubMed:10341243). Phosphorylated on Thr-743 in neuronal cells by Cdc5 kinase and Mapk10, in dividing cells by Cdc2 kinase in a cell-cycle dependent manner with maximal levels at the G2/M phase and, in vitro, by GSK-3-beta (PubMed:11146006, PubMed:8131745). The Thr-743 phosphorylated form causes a conformational change which reduces binding of Fe65 family members (PubMed:11517218). In dopaminergic (DA) neurons, phosphorylation on Thr-743 by LRKK2 promotes the production and the nuclear translocation of the APP intracellular domain (AICD) which induces DA neuron apoptosis (PubMed:28720718). Phosphorylation on Tyr-757 is required for SHC binding (PubMed:11877420). Phosphorylated in the extracellular domain by casein kinases on both soluble and membrane-bound APP. This phosphorylation is inhibited by heparin (PubMed:8999878)
•Extracellular binding and reduction of copper, results in a corresponding oxidation of Cys-144 and Cys-158, and the formation of a disulfide bond. In vitro, the APP-Cu(+) complex in the presence of hydrogen peroxide results in an increased production of amyloid-beta-containing peptides
•Trophic-factor deprivation triggers the cleavage of surface APP by beta-secretase to release sAPP-beta which is further cleaved to release an N-terminal fragment of APP (N-APP)
•Amyloid-beta peptides are degraded by IDE
•Sulfated on tyrosine residues