Source: http://cegg.unige.ch/insecta/immunodb/

TEPs: Thio-Ester Containing Proteins
Summary

Stephanie Bandin and Elena Levashina 

Institute de Biologie Moleculaire et Cellulaire, UPR 9022 CNRS, Strasbourg 67084, France 

The family of thioester-containing proteins (TEPs) comprises vertebrate complement factors C3/C4/C5 and the pan protease inhibitors alpha2-macroglobulins, which are involved in pathogen recognition and activation of immune responses. Insect TEPs could be separated in two main groups: (i) the highly conserved orthologous trio (DmTep6/AgTEP13/AaTEP13) and (ii) much more divergent sequences mostly grouped in species-specific expansions. The group of the three orthologous TEPs is supported by the presence of additional sequence stretches absent from other TEPs. Interestingly these three TEPs do not have the thioester motif (marked with "TE" on the tree) that gives name to the family. The more divergent TEPs are split in two groups: one comprising both Dm and mosquito sequences, all of them bearing the thioester. The second group contains only mosquito TEPs which are divided in species-specific expansions. In this group, some TEPs have lost their thioester motif. The best characterized insect TEP, AgTEP1, binds to pathogen surfaces and promotes phagocytosis of bacteria by mosquito blood cells and killing of Plasmodium parasites [Levashina et al. 2001; Blandin et al. 2004; Moita et al. 2005]. It belongs to the Ag-specific expansion, with no clear 1-1 ortholog in Aa.