Consensus translational initiation sites of marine invertebrate phyla

The efficiency of translational initiation depends upon the sequence contex t surrounding the AUG codon (1, 2, 3). A purine at position -3 contributes critically to context, but other neighboring nucleotides are also important . Nucleotide frequencies at these neighboring positions vary among distant taxa (4, 5). We have analyzed the translational initiation sites of cnidari an, echinoderm, molluscan, annelid, and crustacean sequences in nucleotide sequence databases. These taxa conform to the pattern of a strong preferenc e for a purine at -3, but the frequencies of nucleotides at neighboring pos itions are characteristic for each taxon. The consensus translational initi ation sequences of the marine invertebrate taxa are also different from tho se of vertebrates and single-celled eukaryotes. These consensus sequences a re useful guides for predicting translational initiation sites in cDNA clon es.