Neurogenic locus Notch 2 (IPR022336)
Short name: Notch_2
Overlapping homologous superfamilies
- Notch (IPR008297)
- Neurogenic locus Notch 2 (IPR022336)
Notch cell surface receptors are large, single-pass type-1 transmembrane proteins found in a diverse range of metazoan species, from human to Caenorhabditis species. The fruit fly, Drosophila melanogaster, possesses only one Notch protein, whereas in C.elegans, two receptors have been found; by contrast, four Notch paralogues (designated N1-4) have been identified in mammals, playing both unique and redundant roles.
The hetero-oligomer Notch comprises a large extracellular domain (ECD), containing 10-36 tandem Epidermal Growth Factor (EFG)-like repeats, which are involved in ligand interactions; a negative regulatory region, including three cysteine-rich Lin12-Notch Repeats (LNR); a single trans-membrane domain (TM); a small intracellular domain (ICD), which includes a RAM (RBPjk-association module) domain; six ankyrin repeats (ANK), which are involved in protein-protein interactions; and a PEST domain. Drosophila Notch also contains an OPA domain [PMID: 19379690].
Notch signalling is an evolutionarily conserved pathway involved in a wide variety of developmental processes, including adult homeostasis and stem cell maintenance, cell proliferation and apoptosis [PMID: 10221902]. Notch is activated by a range of ligands -the so-called DSL ligands (Delta/Seratte/LAG-2). Activation is also mediated by a sequence of proteolytic events: ligand binding leads to cleavage of Notch by ADAM proteases [PMID: 12354787] at site 2 (S2) and presenilin-1/g-secretase at sites 3 (S3)and 4 (S4) [PMID: 10206645].The last cleavage releases the Notch intracellular part of the protein (NICD) from the membrane and, upon release, the NICD translocates to the nucleus where it associates with a CBF1/RBJk/Su(H)/Lag1 (CSL) family of DNA-binding proteins. The subsequent recruitment of a co-activator mastermind like (MAML1) protein [PMID: 11101851] promotes transcriptional activation of Notch target genes: well established Notch targets are the Hes and Hey gene families.
Aberrant Notch function and signalling has been associated with a number of human disorders, including Allagile syndrome, spondylocostal dysostosis, aortic valve disease, CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy), and T-cell Acute Lympho-blastic Leukemia (T-ALL); it has also been implicated in various human carcinomas [PMID: 12668592, PMID: 16429119].
Notch 2 has a widespread expression pattern. It is expressed in a number of tissues, including brain, heart, kidney, lung, teeth, skeletal muscle and liver.
- PR01985 (NOTCH2)