Associates with the EF-Tu.GDP complex and induces the exchange of GDP to GTP (By similarity). It remains bound to the aminoacyl-tRNA.EF-Tu.GTP complex up to the GTP hydrolysis stage on the ribosome (By similarity). Binds to psbD and psbA 5'-untranslated regions (UTRs) in vitro. Component of the chloroplast ribosome 30S and 70S subunits, as well as polysomes. Component of the chloroplast ribosome 70S subunit, and at low levels, present in polysomes. Associates transiently with chloroplast polysomes. Probable substrate for the chloroplast protease ClpP6. Defective embryo arrested at globular stage. Belongs to the EF-Ts family.