Aligned RegA proteins of 26 T4-related phages. regA is immediately distal to gene 62 in the core DNA replication gene cluster of all T4-related genomes sequenced to date. Identity relative to T4 RegA is in column 2, aligned amino acids are shown using ClustalW colors, and dashes are gaps in the alignment. Residues numbered above the sequences reference the T4 protein. Asterisks mark the amino acids cited in the text as involved in RNA binding. At the bottom of the alignment are underlined structural elements of the protein from PDB 1REG. Sequences were obtained from GenBank or the T4-like phage genome browser (http://phage.ggc.edu/).