| Elk‑1 is a member of the ternary complex factor (TCF) subfamily of ETS‑domain transcription factors that partners with serum response factor (SRF) at serum response elements (SREs) to control immediate‑early and growth‑responsive gene expression in response to serum, growth factors, and stress. Elk‑1 contains an N‑terminal ETS DNA‑binding domain, a central SRF‑interacting B‑box region, and a C‑terminal transcriptional activation domain (TAD) harboring a cluster of serine‑ and threonine‑rich motifs whose phosphorylation by MAPKs and other kinases regulates Elk‑1 activity, with Ser383 representing a key regulatory site. Elk‑1 is directly phosphorylated by ERK, p38, and stress‑activated JNK at the TAD, and ERK‑dependent phosphorylation of Ser383 and adjacent residues not only increases Elk‑1 binding to the Elk‑1–SRF–SRE ternary complex but also promotes recruitment of coactivators such as p300/CBP and the Mediator subunit MED23, thereby stimulating histone acetylation, Mediator‑dependent pre‑initiation‑complex assembly, and rapid induction of SRE‑driven genes such as c‑fos and Egr1. Mitogen‑dependent phosphorylation of Elk‑1 drives nuclear translocation, SRE‑linked chromatin remodeling, and transcriptional programs tied to synaptic activity and plasticity, whereas sumoylation‑dependent cytoplasmic sequestration and multisite phosphorylation by SAPKs like JNK tune the balance between activation and repression, and Elk‑1 deregulation has been implicated in proliferative signaling, stress responses, and neurodegenerative and oncogenic contexts. |
Lane 1: SNU-1, Lane 2: KATI Ⅲ
