The nucleotide (nt) sequence of a cDNA cloned from the mosquito Anopheles gambiae was determined. The amino acid (aa) sequence of the deduced protein was 56% identical (60/108 aa) to the recently discovered translation initiation factor Suil of yeast, suggesting that the two proteins are homologs and have similar functions. Database searches also revealed strong similarity to other sequences, including the deduced gene products of cDNAs from organisms as diverse as nematodes, humans and plants. The functions of these putative proteins are unknown, but their homology to Suil suggests that they represent an important component of the eukaryotic translation initiation complex.