A multiprotein initiator factor complex (43S). eIF-1 is a low molecular weight factor (113 aa) critical for stringent AUG selection, eIF-2 has three subunits: α (315 aa), β (333 aa, a guanine nucleotide exchange factor), and γ (472 aa), and forms a ternary complex with Met-tRNAi and GTP. eIF-3 contains at least eight distinct polypeptides and plays a role in recycling of ribosomal subunits. eIF-4 is trimeric (eIF-4A, eIF-4E, and eIF-4G) and associates with the 5′ cap of mRNA. eIF-5 interacts with the 40S ribosomal initiation complex and promotes the hydrolysis of bound GTP and subsequent release of eIF-3 from the 40S subunit. The 40S subunit is then able to interact with the 60S ribosomal subunit to form the functional 80S initiation complex.
Subjects: Medicine and Health.