Elk-1: ProductsElk-1 is a member of the ETS family of serum response element-binding transcription factors. It contains an N-terminal ETS DNA-binding domain, a serum response factor (SRF) binding segment (B box), a MAPK docking site (D domain), and a C-terminal transactivation domain (C domain). Elk-1 is normally SUMOylated on R230, R249 and R254. This interferes with nuclear localization and activation. It is also bound to p300 in an inactive complex. Phosphorylation by MAPK1 at S383 and S389 removes SUMO protein, allowing for nuclear localization, and activation of the pre-existing p300/Elk-1 complex that is capable of rapidly initiating gene transcription.