This gene encodes a multifunctional protein that localizes to both the cytoplasm and nucleus. In the cytoplasm, the encoded protein is an auxiliary component of the macromolecular aminoacyl-tRNA synthase complex. However, its mouse homolog has been shown to translocate to the nucleus in response to DNA damage, and it plays a positive role in ATM/ATR-mediated p53 activation. Alternative splicing results in multiple transcript variants. Read-through transcription also exists between this gene and the neighboring downstream MUTED (muted homolog) gene. An EEF1E1-related pseudogene has been identified on chromosome 2.

Positive modulator of ATM response to DNA damage. Component of the multisynthase complex which is comprised of a bifunctional glutamyl-prolyl-tRNA synthase, the monospecific isoleucyl, leucyl, glutaminyl, methionyl, lysyl, arginyl and aspartyl-tRNA synthases, and three auxiliary proteins, EEF1E1/p18, AIMP2/p38 and AIMP1/p43. Interacts with ATM and ATR. The interaction with ATM, which takes place independently of TP53, is induced by DNA damage that may occur during genotoxic stress or cell growth. The interaction with ATR is enhanced by UV irradiation.