 The mouse IgG1 analogue is a tetrapeptide Thr-Gln-Pro-Arg at the same place, one base change at the first base of the triplet code.Tuftsin sequence appears in residues 9-12 from the amino terminal of p12 protein of Rauscher murine leukemia virus.The tetrapeptide Thr-Arg-Pro-Lys is in the influenza hemagglutinin virus protein, residues 214–217.