摘要
Dear Editor, Tumor necrosis factor （TNF） family ligands in vertebrates are type Ii transmembrane proteins with functions in the regulation of immunity, bone homeostasis and more [1]. Drosophila expresses a single TNF homologue, Eiger [2, 3], which contains in addition to the homotrimeric C-terminal TNF homology domain （THD） an extended extracellular portion harboring potential pro- tease cleavage sites （Figure 1A-i）. One of these sites （Val 145） was identified experimentally [4]. A second potential cleavage site （Arg 211） resembling a canonical furin consensus sequence （R-K-S-R compared to R-X-R/K-R） was cleaved by a furin-like activity when expressed in mammalian 293T cells （Supplementary information, Figure S1）. Eiger modulates host responses to Salmonella infections and resistance against extracellular pathogens in Drosophila [5, 6]. When expressed in the eye, it induces cell death via a well-defined pathway （Figure 1 B） [2, 3, 7]. The structural requirements for Eiger＇s activity are however unknown.
