ELK1

ETS Like-1 protein Elk-1 is a protein that in humans is encoded by the ELK1. Elk-1 functions as a transcription activator. It is classified as a ternary complex factor (TCF), a subclass of the ETS family, which is characterized by a common protein domain that regulates DNA binding to target sequences. Elk1 plays important roles in various contexts, including long-term memory formation, drug addiction, Alzheimer's disease, Down syndrome, breast cancer, and depression.

== Structure == thumb|left|Figure 1 As depicted in Figure 1, the Elk1 protein is composed of several domains. Localized in the N-terminal region, the A domain is required for the binding of Elk1 to DNA. This region also contains a nuclear localization signal (NLS) and a nuclear export signal (NES), which are responsible for nuclear import and export, respectively. The B domain allows Elk1 to bind to a dimer of its cofactor, serum response factor (SRF). Located adjacent to the B domain, the R domain is involved in suppressing Elk1 transcriptional activity. This domain harbors the lysine residues that are likely to undergo SUMOylation, a post-translational event that strengthens the inhibition function of the R domain. The D domain plays the key role of binding to active Mitogen-activated protein kinases (MAPKs). Located in the C-terminal region of Elk1, the C domain includes the amino acids that actually become phosphorylated by MAPKs. In this region, Serine 383 and 389 are key sites that need to be phosphorylated for Elk1-mediated transcription to occur. Finally, the DEF domain is specific for the interaction of activated extracellular signal-regulated kinase (Erk), a type of MAPK, with Elk1.