Bacterial initiation factor 2

[1] IF2 binds to an initiator tRNA and controls the entry of tRNA onto the ribosome.

IF2, bound to GTP, binds to the 30S P site.

After associating with the 30S subunit, fMet-tRNAf binds to the IF2 then IF2 transfers the tRNA into the partial P site.

When the 50S subunit joins, it hydrolyzes GTP to GDP and Pi, causing a conformational change in the IF2 that causes IF2 to release and allow the 70S ribosome to form.

Human mitochondria use a nuclear-encoded homolog, MTIF2, for translation initiation.