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Numb Phosphotyrosine-binding (PTB) domain Numb is a membrane associated adaptor protein which plays critical roles in cell fate determination. Numb proteins are involved in control of asymmetric cell division and cell fate choice, endocytosis, cell adhesion, cell migration, ubiquitination of specific substrates and a number of signaling pathways (Notch, Hedgehog, p53). Mutations in Numb plays a critical role in disease (cancer). Numb has an N-terminal PTB domain and a C-terminal NumbF domain. PTB domains have a common PH-like fold and are found in various eukaryotic signaling molecules. This domain was initially shown to binds peptides with a NPXY motif with differing requirements for phosphorylation of the tyrosine, although more recent studies have found that some types of PTB domains can bind to peptides lack tyrosine residues altogether. In contrast to SH2 domains, which recognize phosphotyrosine and adjacent carboxy-terminal residues, PTB-domain binding specificity is conferred by residues amino-terminal to the phosphotyrosine. PTB domains are classified into three groups: phosphotyrosine-dependent Shc-like, phosphotyrosine-dependent IRS-like, and phosphotyrosine-independent Dab-like PTB domains. This cd is part of the Dab-like subgroup. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",