This entry represents the N-terminal domain found in a family of neurogenic mastermind-like proteins (MAMLs), which act as critical transcriptional co-activators for Notch signaling [, , ]. Notch receptors are cleaved upon ligand engagement and the intracellular domain of Notch shuttles to the nucleus. MAMLs form a functional DNA-binding complex with the cleaved Notch receptor and the transcription factor CSL, thereby regulating transcriptional events that are specific to the Notch pathway. MAML proteins may also play roles as key transcriptional co-activators in other signal transduction pathways as well, including: muscle differentiation and myopathies (MEF2C) [], tumour suppressor pathway (p53) []and colon carcinoma survival (beta-catenin) []. MAML proteins could mediate cross-talk among the various signaling pathways and the diverse activities of the MAML proteins converge to impact normal biological processes and human diseases, including cancers.The N-terminal domain of MAML proteins adopt an elongated kinked helix that wraps around ANK and CSL forming one of the complexes in the build-up of the Notch transcriptional complex for recruiting general transcription factors []. This N-terminal domain is responsible for its interaction with the ankyrin repeat region of the Notch proteins NOTCH1 [], NOTCH2 [], NOTCH3 []and NOTCH4. It forms a DNA-binding complex with Notch proteins and RBPSUH/RBP-J kappa/CBF1, and also binds CREBBP/CBP []and CDK8 []. The C-terminal region is required for transcriptional activation.
This family includes the neurogenic mastermind-like proteins 1-3 (MAML1-3) from chordates, which act as critical transcriptional co-activators for Notch signaling [, ]. Notch receptors are cleaved upon ligand engagement and the intracellular domain of Notch shuttles to the nucleus. MAMLs form a functional DNA-binding complex with the cleaved Notch receptor and the transcription factor CSL, thereby regulating transcriptional events that are specific to the Notch pathway. MAML proteins may also play roles as key transcriptional co-activators in other signal transduction pathways as well, including: muscle differentiation and myopathies (MEF2C) [], tumour suppressor pathway (p53) []and colon carcinoma survival (beta-catenin) []. MAML proteins could mediate cross-talk among the various signaling pathways and the diverse activities of the MAML proteins converge to impact normal biological processes and human diseases, including cancers.They consist of an N-terminal domain which adopt an elongated kinked helix that wraps around ANK and CSL forming one of the complexes in the build-up of the Notch transcriptional complex for recruiting general transcription factors [, ]]. This N-terminal domain is responsible for its interaction with the ankyrin repeat region of the Notch proteins NOTCH1 [], NOTCH2 [], NOTCH3 []and NOTCH4. It forms a DNA-binding complex with Notch proteins and RBPSUH/RBP-J kappa/CBF1, and also binds CREBBP/CBP []and CDK8 []. The C-terminal region is required for transcriptional activation.
This entry represents the N-terminal domain found in a family of neurogenic mastermind-like proteins (MAMLs), which act as critical transcriptional co-activators for Notch signaling [, , ]. Notch receptors are cleaved upon ligand engagement and the intracellular domain of Notch shuttles to the nucleus. MAMLs form a functional DNA-binding complex with the cleaved Notch receptor and the transcription factor CSL, thereby regulating transcriptional events that are specific to the Notch pathway. MAML proteins may also play roles as key transcriptional co-activators in other signal transduction pathways as well, including: muscle differentiation and myopathies (MEF2C) [], tumour suppressor pathway (p53) []and colon carcinoma survival (beta-catenin) []. MAML proteins could mediate cross-talk among the various signaling pathways and the diverse activities of the MAML proteins converge to impact normal biological processes and human diseases, including cancers.The N-terminal domain of MAML proteins adopt an elongated kinked helix that wraps around ANK and CSL forming one of the complexes in the build-up of the Notch transcriptional complex for recruiting general transcription factors []. This N-terminal domain is responsible for its interaction with the ankyrin repeat region of the Notch proteins NOTCH1 [], NOTCH2 [], NOTCH3 []and NOTCH4. It forms a DNA-binding complex with Notch proteins and RBPSUH/RBP-J kappa/CBF1, and also binds CREBBP/CBP []and CDK8 []. The C-terminal region is required for transcriptional activation.
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 []. 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 []. 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 []at site 2 (S2) and presenilin-1/g-secretase at sites 3 (S3)and 4 (S4) [].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 []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 [, ]. Notch3 displays a more restrictive distribution than the rest of the Notch subtypes, being expressed predominantly in vascular smooth muscle cells, the central nervous system, certain thymocytes subsets, and in regulatory T cells [].
