Disease:Defects in PSEN1 are a cause of Alzheimer disease type 3 (AD3) [MIM:607822]. AD3 is a familial early-onset form of Alzheimer disease. Alzheimer disease is a neurodegenerative disorder characterized by progressive dementia , loss of cognitve abilities , and deposition of fibrillar amyloid proteins as intraneuronal neurofibrillary tangles , extracellular amyloid plaques and vascular amyloid deposits. The major constituent of these plaques is the neurotoxic amyloid-beta-APP 40-42 peptide (s) , derived proteolytically from the transmembrane precursor protein APP by sequential secretase processing. The cytotoxic C-terminal fragments (CTFs) and the caspase-cleaved products such as C31 derived from APP , are also implicated in neuronal death. ,Disease:Defects in PSEN1 are a cause of frontotemporal dementia [MIM:600274]. ,Domain:The PAL motif is required for normal active site conformation. ,Function:Probable catalytic subunit of the gamma-secretase complex , an endoprotease complex that catalyzes the intramembrane cleavage of integral membrane proteins such as Notch receptors and APP (beta-amyloid precursor protein) . Requires the other members of the gamma-secretase complex to have a protease activity. May play a role in intracellular signaling and gene expression or in linking chromatin to the nuclear membrane. Stimulates cell-cell adhesion though its association with the E-cadherin/catenin complex. Under conditions of apoptosis or calcium influx , cleaves E-cadherin promoting the disassembly of the E-cadherin/catenin complex and increasing the pool of cytoplasmic beta-catenin , thus negatively regulating Wnt signaling. May also play a role in hematopoiesis. ,online information:Presenilins mutations ,PTM:After endoproteolysis , the C-terminal fragment (CTF) is phosphorylated on serine residues by PKA and/or PKC. Phosphorylation on Ser-346 inhibits endoproteolysis. ,PTM:Heterogeneous proteolytic processing generates N-terminal (NTF) and C-terminal (CTF) fragments of approximately 35 and 20 kDa , respectively. During apoptosis , the C-terminal fragment (CTF) is further cleaved by caspase-3 to produce the fragment , PS1-CTF12. ,similarity:Belongs to the peptidase A22A family. ,subcellular location:Bound to NOTCH1 also at the cell surface. Colocalizes with CDH1/2 at sites of cell-cell contact. Colocalizes with CTNNB1 in the endoplasmic reticulum and the proximity of the plasma membrane. Also present in azurophil granules of neutrophils. ,subunit:Homodimer. Component of the gamma-secretase complex , a complex composed of a presenilin homodimer (PSEN1 or PSEN2) , nicastrin (NCSTN) , APH1 (APH1A or APH1B) and PEN2. Such minimal complex is sufficient for secretase activity. Other components which are associated with the complex include SLC25A64 , SLC5A7 , PHB and PSEN1 isoform 3. Predominantly heterodimer of a N-terminal (NTF) and a C-terminal (CTF) endoproteolytical fragment. Associates with proteolytic processed C-terminal fragments C83 and C99 of the amyloid precursor protein (APP) . Associates with NOTCH1. Component of cadherin/catenin adhesion complexes through direct binding to CDH1 or CDH2. Interaction with CDH1 stabilizes the complex and stimulates cell-cell aggregation. Interaction with CDH2 is essential for trafficking of CDH2 from the endoplasmic reticulum to the plasma membrane. Interacts with CTNND2 , CTNNB1 , HERPUD1 , FLNA , FLNB , MTCH1 , PKP4 and PARL. Interacts through its N-terminus with isoform 3 of GFAP. Interacts with DOCK3. ,tissue specificity:Expressed in a wide range of tissues including various regions of the brain , liver , spleen and lymph nodes. ,
展开内容