Xenbase Image ID: 130400

Figure 1. Phosphorylation-Resistant Mad Proteins are Hyperactive.(A) Model summarizing the integration of Dpp, EGFR and Wg signaling at the level of Mad phosphorylations in Drosophila. (B) Diagrams of Mad Wild Type (MWT), Mad MAPK Mutant (MMM) and Mad GSK3 Mutant (MGM) proteins. (C–F) Microinjection of MMM and MGM mRNAs into Xenopus embryos had stronger ventralizing activity than MWT, causing upregulation of sizzled (n = 17, 32, 26, and 30, two independent experiments). Brain markers otx2 and krox20 were repressed. (G–J) Driving MMM and MGM with patched-Gal4 in the anterior wing compartment caused formation of ectopic crossvein-like tissue. This tissue links longitudinal veins two and three in both proximal and distal regions, pulling the two veins closer together. (K–N) Driving phosphorylation-resistant Mads with apterous-Gal4 induced ectopic vein tissue and blistering, indicating increased Dpp signaling. (O) Polyubiquitinylation of Mad requires GSK3 and MAPK phosphorylation sites. Lane 1, 293T cells cotransfected with MWT-Flag, Drosophila Smurf and HA-ubiquitin all cloned in pCS2. The strong smear represents polyubiquitinylated Mad tagged with HA-ubiquitin. Lanes 2 and 3, polyubiquitinylation was greatly decreased in the MMM and MGM mutant proteins. The lower panel shows equal levels of immunoprecipitated Mad (α-Flag). Image published in: Eivers E et al. (2009) Eivers et al. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license Larger Image Printer Friendly View

Return to previous page