Figure 8. Armadillo associates with Notch in Drosophila embryos.

Notch protein was immunoprecipitated from wild type embryos and the presence of associated proteins was assessed by Western blot. The majority of Notch protein present in embryo lysate and immunoprecipitated was the full-length protein (>250 kDa). In Drosophila the predominant form of Notch at the cell surface is full length unlike in mammalian cells, where the majority of Notch molecules at the cell surface are furin cleaved heterodimeric molecule, this lack of furin cleavage does not seem to affect ability of the full length Notch molecule to signal in Drosophila (Kidd and Lieber, 2002). Note Notch protein (lower panel) was not detected in the Protein-G sepharose immunoprecipitation reaction. Detected in associated with immunoprecipitated Notch were both Armadillo (middle panel) and Dishevelled (upper panel) protein. (Axelrod et al., 1996; Zecchini et al., 1999). In these experiments the lysate lane represents 1/20^th of the total protein added to the immunoprecipitation reaction. Typically we observe that the immunoprecipitated Notch reflects about 5-10% of the total Notch present in the lysate, associated with this Notch typically we observe between 0.5 –3% of the total Armadillo present and less than 0.5% of the total Dishevelled present. Given that the pool of Armadillo associated with Notch is not associated with E-cadherin it is only to be expected that this Notch associated fraction of Armadillo is very small protportion of the total cellular Armadillo.