eff2

Eff2 most commonly refers to eukaryotic elongation factor 2 (EF-2), a key component of the cellular translation machinery. The gene symbol is EEF2 in many species, including humans. EF-2 is a GTP-binding protein that drives the translocation step of protein synthesis on the ribosome, moving the peptidyl-tRNA from the A-site to the P-site and the mRNA by one codon per cycle. The protein is highly conserved across eukaryotes and archaea.

EF-2's activity requires GTP hydrolysis and is essential for polypeptide elongation. It acts after peptide bond formation and before translocation; without functional EF-2, elongation stalls and protein synthesis ceases.

Regulation of EF-2 occurs through phosphorylation by EF-2 kinase (EEF2K) in response to cellular stress or energy depletion. Phosphorylation reduces EF-2's affinity for the ribosome and slows translation, providing a mechanism for downregulating protein synthesis under adverse conditions.

Toxins also target EF-2. Diphtheria toxin from Corynebacterium diphtheriae and Pseudomonas aeruginosa exotoxin A catalyze ADP-ribosylation of the diphthamide residue on EF-2, locking the ribosome and inhibiting translocation. This prevents protein synthesis and can lead to cell death.

Beyond its canonical role, EEF2 is studied in cancer biology and neuroscience, where altered EF-2 activity or phosphorylation can influence cell growth, stress responses, and synaptic function. In some literature, eff2 may appear as an alternative notation or in organism-specific contexts, but the primary reference is to eukaryotic elongation factor 2.