Comparison of the protein sequences of CD44. The protein sequence determined from nucleotides of dog is shown on the top line and amino acid differences found in human and mouse (C3H) are presented in the next two lines. Dashes (—) are deletions and the putative transmembrane segment is underlined. Also indicated are the locations of the truncation variants used for peptide mapping with the 5′ end of all the peptides initiating at * and terminating 3′ as indicated (F1-B, F1-C, F2, F3).