Neurogenic locus notch homolog protein 1 negative regulatory region (Notch1 NRR)

The Notch1 negative regulatory region (NRR) is a structural domain of the Notch1 receptor that functions as a molecular switch to control receptor activation. It consists of three Lin-12/Notch repeats (LNR-A, B, and C) and a heterodimerization (HD) domain that non-covalently associates the extracellular and transmembrane subunits (Malecki et al., 2006). In its resting state, the NRR adopts a conformation that sterically masks the S2 cleavage site, preventing its recognition by ADAM10 or ADAM17 metalloproteases (Gordon et al., 2007). Ligand binding provides the mechanical force necessary to pull the LNR repeats away from the HD domain, exposing the S2 site and triggering the proteolytic cascade that releases the Notch intracellular domain (NICD) to regulate gene expression (Wu et al., 2010). Mutations in the NRR, particularly those that destabilize the HD domain, are a hallmark of T-cell acute lymphoblastic leukemia (T-ALL), leading to ligand-independent signaling (Weng et al., 2004). Therapeutic strategies targeting the NRR involve monoclonal antibodies, such as brontictuzumab, which bind and lock the NRR in its autoinhibited state to inhibit oncogenic Notch signaling (Tiyanont et al., 2013).

Other names

Notch1 NRRNotch1 autoinhibitory domainNotch1 LNR-HD domainNotch1 heterodimerization domain

Monoclonal antibodies bind to the NRR to stabilize the autoinhibited conformation, preventing ADAM-mediated S2 cleavage and subsequent downstream signaling (Wu et al., 2010).