EEF-1

eEF-1 is a eukaryotic elongation factor.

Its α and βγ subunits act as counterparts to EF-Tu and EF-Ts, respectively

Genes include:
 * EEF1A1, EEF1A2, EEF1A3
 * EEF1B1, EEF1B2, EEF1B3, EEF1B4
 * EEF1D, EEF1E1, EEF1G

Various species of green algae, red algae, chromalveolates, and fungi lack the EF-1α gene but instead possess a related gene called EFL (elongation factor-like). Although its function has not be studied in depth, it appears to be similar to EF-1α. Only two organisms are known to have both EF-1α and EFL: the fungus Basidiobolus and the diatom Thalassiosira. The evolutionary history of EFL is unclear. It may have arisen one or more times followed by loss of EFL or EF-1α. The presence in three diverse eukaryotic groups (fungi, chromalveolates, and archaeplastida) is supposed to be the result of two or more horizontal gene transfer events.