CLONING AND SEQUENCING OF CDNA-ENCODING HAPTOGLOBIN, AN ACUTE-PHASE PROTEIN IN SYRIAN-HAMSTER, MESACRICETUS-AURATUS

One of the most prominent acute phase proteins in Syrian hamster (Mesa cricetus auratus) was identified as haptoglobin and cDNA encoding this protein was sequenced. The deduced amino acid sequence of the mature protein is 83.6, 80.5, 79.6, and 76.1% identical to those of mouse, ra t, human (1 s isoform), and dog homologues, respectively. As compared with six known members of this family, including human haptoglobin-rel ated protein, hamster haptoglobin had 11 unique substitutions and one unique codon deletion, that is, the corresponding residues have been c onserved in all other members. This indicates that hamster haptoglobin gene has accumulated these unique mutations after the time of criceti d murid split while the ancestral sequence has been conserved in all o ther species examined. Hamster haptoglobin, however, contains nine cys teine residues, all of which are found in conserved positions in prima te and rodent homologues. Molecular phylogenetic trees of alpha- and b eta-chains show that the alpha-chain is more divergent than the beta-c hain and that the difference in genetic distance between canine and ha mster alpha-chains is much greater than that of corresponding beta-cha ins. (C) 1998 Elsevier Science Inc.