Associates with the EF-Tu.GDP complex and induces the exchange of GDP to GTP (PubMed:15548736). It remains bound to the aminoacyl-tRNA.EF-Tu.GTP complex up to the GTP hydrolysis stage on the ribosome (PubMed:15548736). Binds to psbD and psbA mRNAs 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. Visible only at the end of the dark period, in 12 hours light/ 12 hours dark conditions (at protein level) (PubMed:15548736). Induced transiently upon shifting to light; mostly expressed after shifting to light, to a lower extent at the end of the dark period and under continuous light, and at low levels at the end of the light period (PubMed:15548736). Induced transiently upon shifting to light; mostly expressed after shifting to light, tand at low levels at the end of the light and dark periods and under continuous light. Induced transiently upon shifting to light; mostly expressed after shifting to light, to a lower extent at the end of the dark period and under continuous light, and at low levels at the end of the light period. Expressed constitutively in both continuous light, and 12 hours light/ 12 hours dark conditions (at protein level). Expressed constitutively in both continuous light, and 12 hours light/ 12 hours dark conditions (at protein level). 65 kDa protein PSRP-7 is the major form. Belongs to the EF-Ts family.