EVOLUTION OF THE SERUM AMYLOID-A (SAA) PROTEIN SUPERFAMILY

The serum amyloid A (SAA) superfamily comprises a number of genes and proteins characterized from a range of mammalian species. The majority of members described to date are dramatically induced during the acut e-phase response, suggesting an important shortterm beneficial role in the response to tissue injury and inflammation. However, important di sease associations have also been proposed for certain SAAs during chr onic inflammation. The nomenclature of many of the superfamily members has been the result of comparisons with previously reported sequences implying disease association and/or functional relatedness between su ch members. The evolutionary relationships of the SAA superfamily memb ers have been investigated by comparisons at both the amino acid and t he nucleotide level. The results indicate that all members of the supe rfamily within a species have been undergoing concerted evolution. Thi s has important implications in ascribing functions and disease associ ations to individual SAA superfamily members and indicates that design ations should not be based on the extent of amino acid identity alone but should be made only following direct experimental observation of t he proteins themselves. (C) 1991 Academic Press, Inc.