Serpins are a group of proteins involved in the regulation of serine and other type of proteases, and have been identified in many kinds of organisms from invertebrates to vertebrates. Serpins are known to regulate the proteolytic cascades of the innate immune pathways in addition to their roles in blood coagulation, angiogenesis, fibrinolysis, inflammation and tumor suppression. In this study, we have isolated two partial serpin gene fragments from expressed sequence tags (ESTs) of Nesiohelix samarangae. Dotplot analysis indicates that they are of two different types, Ns-serpin type 1 and Ns-serpin type 2. Ns-serpin type 1 has 819 bp coding region (272 amino acids), whereas Ns-serpin type 2 has 555 bp coding region (185 amino acids). Molecular phylogenetic analysis shows that the identified serpins have high similarities to their counterparts in the California see slug, Aplysia californica. Yet, the precise biological and immunological roles of these Ns-serpins remain to be further investigated using RNA interference and other molecular techniques.
