Figure 4.
Ndfip proteins can activate Su(dx). A, domain organization of Drosophila Notch. B, sequence alignment of Drosophila Ndfip (dNdfip) and human Ndfip1 (hNdfip1). Three PY motifs are indicated with a red rectangular box. C, hNdfip1 can efficiently activate Su(dx). D, effects of dNdfip WT or PY mutants on Su(dx) autoubiquitination. E, GST-dNdfip can robustly pull down Su(dx) WW12L34, WW12L, and LWW34, whereas GST-Notch PY can only pull down WW12L34 and LWW34 but not WW12L. F, ITC-based measurement of the binding affinities between dNdfip and Su(dx) WW34 or WW12L34. G and H, MBP pulldown assay of MBP-tagged 12L34HECT WT and various mutants with an increasing amount of Trx-dNdfip. In this assay, the molar ratios of dNdfip and Su(dx) were 1:1, 2:1, and 5:1, and the quantification data of dNdfip pulled down by Su(dx) are shown at the bottom.
