Epl1

Elp1, sometimes written as Epl1 in database entries, is a conserved subunit of the Elongator complex. The Elongator complex is a six-subunit assembly (Elp1–Elp6) that participates in two major cellular pathways: transcription elongation by RNA polymerase II and the cytoplasmic modification of tRNA, including formation of the mcm5s2U wobble uridine modification. Elp1 is regarded as a scaffolding component that helps assemble and stabilize the complex and facilitates interactions with other factors involved in transcription and tRNA processing. The complex is primarily localized in the nucleus, with additional associations in the cytoplasm under certain conditions, and its activity can be modulated by cellular state and stress.

In transcription, the Elongator complex is proposed to assist RNA polymerase II during elongation, influencing gene expression programs. In tRNA biology, Elongator-dependent modifications at the wobble position of uridine (U34) affect codon-anticodon pairing, translation efficiency, and proteome quality, linking Elp1-containing complexes to both gene expression and translational control. The exact contributions of Elp1 can vary among organisms, but the subunit is consistently identified as part of the core Elongator architecture that enables these dual roles.

Clinical relevance is most often associated with the human ELP1 gene, which encodes the Elp1 protein. Pathogenic variants in ELP1 cause familial dysautonomia (Riley-Day syndrome), a congenital neuropathy characterized by autonomic and sensory dysfunction. In model organisms, loss or mutation of ELP1-equivalent subunits typically leads to defective tRNA modification, altered translation, and growth or stress-response phenotypes, underscoring the essential nature of Elp1 within the Elongator complex.