A remarkable amino acid sequence homology between a phage T4 tail fibre protein and ORF314 of phage lambda located in the tail operon.

We have found that the amino acid (aa) sequence of the tip of phage T4 tail fibre (gene 37) shows more than 50% homology with the aa sequence predicted from an open reading frame (ORF314) in the phage lambda genome. ORF314 is near the 3' end of the late morphogenetic operon, beyond gene J coding for the lambda tail fibre. The homologous sequences are for the most part composed of repeated aa, the most remarkable of which is a Gly-X-His-Y-His motif where X and Y are small, uncharged aa, found six times in the T4 protein and seven times in the lambda ORF314 sequence.