 Upon base pairing of the AUG-codon with the Met-tRNA, eIF5 (which is a GTPase-activating protein , or GAP) is recruited to the complex and induces eIF2 to hydrolyse its GTP.This causes eIF2-GDP to be released from this 48S complex and translation begins after recruitment of the 60S ribosomal sub-unit and formation of the 80S initiation complex.Finally, with the help of the Guanine nucleotide exchange factor (GEF) eIF2B, the GDP in eIF2 is exchanged for a GTP and the ternary complex reforms for a new round of translation initiation.