| Translation initiation factor IF-3, N-terminal domain | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 translation initiation factor 3 n-terminal domain | |||||||||
| Identifiers | |||||||||
| Symbol | IF3_N | ||||||||
| Pfam | PF05198 | ||||||||
| InterPro | IPR019814 | ||||||||
| PROSITE | PDOC00723 | ||||||||
| SCOP2 | 1tif /SCOPe /SUPFAM | ||||||||
| |||||||||
| Translation initiation factor IF-3, C-terminal domain | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 translation initiation factor 3 c-terminal domain | |||||||||
| Identifiers | |||||||||
| Symbol | IF3_C | ||||||||
| Pfam | PF00707 | ||||||||
| InterPro | IPR019815 | ||||||||
| PROSITE | PDOC00723 | ||||||||
| SCOP2 | 1tif /SCOPe /SUPFAM | ||||||||
| |||||||||
In molecular biology,translation initiation factor IF-3 (gene infC) is one of the three factors required for the initiation ofprotein biosynthesis inbacteria. IF-3 is thought to function as a fidelity factor during the assembly of theternary initiationcomplex which consists of the30S ribosomal subunit, the initiatortRNA and themessenger RNA. IF-3 is abasic protein that binds to the 30S ribosomal subunit.[1] Thechloroplast homolog enhances the poly(A,U,G)-dependent binding of the initiator tRNA to its ribosomal 30ssubunits.[2]IF1–IF3 may also perform ribosome recycling.[3]
IF3 is not universally found in all bacterial species. However, inE. coli, it is required for the30S subunit to bind to the initiation site inmRNA. In addition, it has several other jobs including the stabilization of free 30S subunits, enables 30S subunits to bind to mRNA and checks for accuracy against the firstaminoacyl-tRNA. It also allows for rapid codon-anticodon pairing for the initiatortRNA to bind quickly. IF3 is required by the small subunit to form initiation complexes, but has to be released to allow the50S subunit to bind.
IF3 is made up of two domains connected by a flexible linker. Together they allow IF3 to carry out its function.[4]
Humanmitochondria use a nuclear-encoded homologMTIF3 for translation initiation.[5] Some bacteria, chloroplasts, and mitochondria have multiple copies of IF3.[6]