| Summary: | <p>Abstract</p> <p>Background</p> <p>The superfamily of <b><it>ser</it></b>ine <b><it>p</it></b>roteinase <b><it>in</it></b>hibitors (serpins) is involved in numerous fundamental biological processes as inflammation, blood coagulation and apoptosis. Our interest is focused on the SERPINA3 sub-family. The major human plasma protease inhibitor, α1-antichymotrypsin, encoded by the <it>SERPINA3 </it>gene, is homologous to genes organized in clusters in several mammalian species. However, although there is a similar genic organization with a high degree of sequence conservation, the reactive-centre-loop domains, which are responsible for the protease specificity, show significant divergences.</p> <p>Results</p> <p>We provide additional information by analyzing the situation of <it>SERPINA3 </it>in the bovine genome. A cluster of eight genes and one pseudogene sharing a high degree of identity and the same structural organization was characterized. Bovine <it>SERPINA3 </it>genes were localized by radiation hybrid mapping on 21q24 and only spanned over 235 Kilobases. For all these genes, we propose a new nomenclature from <it>SERPINA3-1 </it>to <it>SERPINA3-8</it>. They share approximately 70% of identity with the human <it>SERPINA3 </it>homologue. In the cluster, we described an original sub-group of six members with an unexpected high degree of conservation for the reactive-centre-loop domain, suggesting a similar peptidase inhibitory pattern. Preliminary expression analyses of these bovSERPINA3s showed different tissue-specific patterns and diverse states of glycosylation and phosphorylation. Finally, in the context of phylogenetic analyses, we improved our knowledge on mammalian SERPINAs evolution.</p> <p>Conclusion</p> <p>Our experimental results update data of the bovine genome sequencing, substantially increase the bovSERPINA3 sub-family and enrich the phylogenetic tree of serpins. We provide new opportunities for future investigations to approach the biological functions of this unusual subset of serine proteinase inhibitors.</p>
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