FIG. 1.

Predicted structure of engineered Notch polypeptides. cDNAs encoding Drosophila Notch and various forms of human Notch1 were assembled and expressed in Drosophila S2 and mammalian cell lines, respectively, as described in Materials and Methods. dN, full-length Drosophila Notch; N^EC, Notch extracellular subunit; N^TM, Notch transmembrane subunit; L, leader peptide; HA, hemagglutinin tag; C, conserved cysteine residues; P, PEST sequence; N1HA, HA epitope-tagged human Notch 1; ΔEGF, a form of hN1 lacking all 36 EGF repeats; ΔLN-HA, a form of hN1 with the three LN module repeats deleted; N^TM, a form of hN1 with an amino terminus 69 amino acids external to the transmembrane domain.