During the scanning for AUG start codon, the N-terminal GTPase activating protein (GAP) domain of eIF5 interacts with the G-domain of eIF2γ subunit to trigger GTP hydrolysis to form GDP and P i. The factor eIF1 binds near P-site to monitors anti-codon:codon interaction and prevents non-AUG codon selection 1, 2. The factor eIF1A binds to the A-site of the ribosome and promotes mRNA scanning by its C-terminal tail (CTT) 5.
The mRNA binds to the eIF4F complex through its 5′ m 7Gppp cap and it is recruited laterally to the PIC by placing the mRNA into the mRNA entry channel results in the formation of 48S initiation complex 3, 4. The Saccharomyces cerevisiae translation initiation factors critical for the start codon selection consist of eIF2-GTP-Met-tRNA i Ternary complex (TC), eIF1, eIF1A, eIF5, eIF3, and 40S ribosomal subunit together constitute 43S pre-initiation complex (PIC) that is involve in the selection of AUG start codon on the mRNA 1, 2.
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In eukaryotic translation initiation, the AUG start codon is predominantly selected to establish an open reading frame (ORF) to decode the genetic code while scanning the mRNA from 5′ to 3′ direction by the translation initiation machinery.
However, no studies have been conducted to understand the change in cellular proteome and its effects on cellular physiology caused by the defect in eukaryotic translation initiation factor fidelity. Defect in the genes involved in the general translation initiation that alters the fidelity of start codon selection could have a pleiotropic effect on cellular function as they change the cellular proteome. The fidelity of start codon selection is critical for the synthesis of a normal proteome.
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