IF1

IF1, or Initiation Factor 1, is a prokaryotic translation initiation factor involved in the early stages of protein synthesis on the small ribosomal subunit. It is commonly encoded by the infA gene and functions alongside the other initiation factors IF2 and IF3 to assemble the initiation complex that begins translation.

The primary role of IF1 is to bind to the A site of the 30S ribosomal subunit, preventing aminoacyl-tRNA entry at that site prematurely. By occupying the A site, IF1 helps ensure that the initiator tRNA, formylmethionyl-tRNAiMet, is correctly positioned at the P site and that the correct start codon is selected. IF1 thus contributes to the accuracy of translation initiation in concert with IF3.

IF1 works with IF3 to hinder premature joining of the 50S subunit and to promote proper initiation. After the initiator tRNA is positioned and the initiator complex is formed, the 50S subunit can join, and GTP hydrolysis by IF2 alongside the action of the initiation factors leads to their release, producing the 70S initiation complex ready for elongation.

Distribution and evolutionary notes indicate that IF1 is widespread among bacteria, though its essentiality can vary by species. In some lineages, deletion or loss of IF1 affects growth or initiation fidelity, while in others it is dispensable under certain conditions. The exact dependence on IF1 can reflect differences in ribosome structure or compensatory mechanisms among bacteria.

Alternatives: The acronym IF1 can denote other, non-related terms in different scientific fields. Context is important to determine the intended meaning of IF1 in a given article or discussion.