ISSN:
1432-1432
Keywords:
Gene families
;
mRNA divergence
;
Alpha-1-proteinase inhibitor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The organization and sequence of genes encoding the α1-proteinase inhibitor (α1PI), a major serine proteinase inhibitor of the mammalian bloodstream, have been compared in several species, including murine rodents (genus Mus). Analysis of gene copy number indicates that amplification of α1PI genes occurred at some time during evolution of the Mus genus, leading to fixation of a family of about three to five genes in several existing species (e.g., M. domesticus and M. saxicola), and only a single gene in others (e.g., M. caroli). A phylogeny for the various mammalian α1PI mRNAs was constructed based upon synonymous substitutions within coding regions. The mRNAs in different murine species diverged from a common ancestor before the formation of the first species lineages of the Mus genus, i.e., about 10–13 million years ago. Thus, α1PI gene amplification must have occurred prior to Mus speciation; gene families were retained in some, but not all, murine species. The reactive center region of the α1PI polypeptide, which determines target protease specificity, has diverged rapidly during evolution of the Mus species, but not during evolution of other mammalian species included in the analysis. It is likely that this accelerated evolution of the reactive center, which has been noted previously for serine proteinase inhibitors, was driven by some sort of a positive Darwinian selection that was exerted in a taxon-specific manner. We suggest that evolution of α1PI genes of murine rodents has been characterized by both modification of gene copy number and rapid reactive center divergence. These processes may have resulted in a broadened repertoire of proteinase inhibitors that was evolutionarily advantageous during Mus speciation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00166159
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