Initiation factor

Initiation factors are proteins that bind to the small subunit of the ribosome during the initiation of translation, a part of protein biosynthesis. Initiation factors are proteins that bind to the small subunit of the ribosome during the initiation of translation, a part of protein biosynthesis. Initiation factors can interact with repressors to slow down or prevent translation or they can interact with activators to help them start  or increase the rate of translation. In bacteria they are simply called Ifs (i.e.., IF1, IF2, & IF3) and in eukaryotes they are known as eIFs (i.e.., eIF1, eIF2, eIF3). In eukaryotic transcription these are also called the general transcription factors, or σ factors