Associates with the EF-Tu.GDP complex and induces the exchange of GDP to GTP. It remains bound to the aminoacyl-tRNA.EF-Tu.GTP complex up to the GTP hydrolysis stage on the ribosome. Expressed in all tissues, with the highest levels of expression in skeletal muscle, liver and kidney. The disease is caused by variants affecting the gene represented in this entry. Belongs to the EF-Ts family.