Fig. 1.

The Drosophila Atf3 protein interacts with Jun. (A) Alignment between bZIP domains of human ATF3 and Drosophila Atf3 shows identical (black shading) and similar (gray) amino acids. (B) Atf3 immunoprecipitated with Jun but not with Fos. S2 cells were transfected with Fos-His alone or together with V5-tagged Atf3; Jun was endogenous. Proteins bound to the anti-V5 antibody were analyzed by western blot (WB) with anti-V5, anti-Jun and anti-Fos antibodies. Cell lysates are shown as input. (C) Electrophoresis mobility shift assay shows binding of isolated bZIP domains of the Atf3 (A), Jun (J) and Fos (F) proteins, single or in combination, to the AP-1 and ATF/CRE consensus elements.