Prokaryotic initiation factor-1 is a prokaryotic initiation factor.

IF1 associates with the 30S

30S

30S is the smaller subunit of the 70S ribosome of prokaryotes. It is a complex of ribosomal RNA and ribonucleoproteins that functions in mRNA translation...

 ribosomal subunit in the A site and prevents an aminoacyl-tRNA

Aminoacyl-tRNA

Aminoacyl-tRNA is tRNA to which its cognated amino acid is adhered. Its role is to deliver the amino acid to the ribosome where it will be incorporated into the polypeptide chain that is being produced...

 from entering. It modulates IF2 binding to the ribosome by increasing its affinity. It may also prevent the 50S

50S

50S is the larger subunit of the 70S ribosome of prokaryotes. It is the site of inhibition for antibiotics such as macrolides, chloramphenicol, clindamycin, and the pleuromutilins. It includes the subunits 5S and 23S.-Structure:...

subunit from binding, stopping the formation of the 70S subunit. It also contains a β-domain fold common for nucleic acid binding proteins.