Chloroplast translation initiation factor that is essential for the coordination of leaf and chloroplast development (PubMed:27535792). IF-3 binds to the 30S ribosomal subunit and shifts the equilibrum between 70S ribosomes and their 50S and 30S subunits in favor of the free subunits, thus enhancing the availability of 30S subunits on which protein synthesis initiation begins (By similarity). Monomer. Highly expressed in young, newly emerged leaves. Chloroplast development defect, and leaf developmental abnormalities, such as virescent and serrated leaf phenotype, disorganized mesophyll cells, and altered cotyledon venation patterns. Belongs to the IF-3 family.