Numb: ProductsNumb is a 75 kDa member of a family of cytoplasmic adaptor proteins termed CLASPS (clathrin-associated sorting proteins). CLASPS link transmembrane cargo proteins to the endocytic machinery. Numb is normally associated with the basolateral surface of polarized cells and has been shown to regulate cell fate by modulating activity of the Notch pathway. Human Numb is 651 amino acids (aa) in length. It contains one phosphotyrosine-binding domain (PTB; aa 24 - 172) and one proline-rich region (PRR; aa 366 - 413). There is a potential for multiple alternate splice forms that involve all regions of the molecule. Over aa 356 - 592, human Numb shares 88% and 90% aa identity with mouse and canine Numb, respectively.