| Description | Sea anemones are a rich source of lethal pore-forming peptides and proteins, known collectively as cytolysins or actinoporins. There are several different groups of cytolysins based on their structure and function, and share conserved regions such as a surface-exposed lipid/carbohydrate-binding module involved in toxin binding to cell membranes providing a non-specific binding to membranes to target a wide range of species and protein-protein binding surfaces that contribute to the oligomerization of membrane-bound actinoporin monomers [ , ]. This entry represents the most numerous group, the 20kDa highly basic peptides. These cytolysins form cation-selective pores in sphingomyelin-containing membranes. Examples include equinatoxins (from Actinia equina), sticholysins (from Stichodactyla helianthus), magnificalysins (from Heteractis magnifica), and tenebrosins (from Actinia tenebrosa), which exhibit pore-forming, haemolytic, cytotoxic, and heart stimulatory activities. This entry also includes related proteins from fish.Cytolysins adopt a stable soluble structure, which undergoes a conformational change when brought in contact with a membrane, leading to an active, membrane-bound form that inserts spontaneously into the membrane. They often oligomerize on the membrane surface, before puncturing the lipid bilayers, causing the cell to lyse. The 20kDa sea anemone cytolysins require a phosphocholine lipid headgroup for binding, however sphingomyelin is required for the toxin to promote membrane permeability [ ]. The crystal structures of equinotoxin II [] and sticholysin II [] both revealed a compact β-sandwich consisting of ten strands in two sheets flanked on each side by two short α-helices, which is a similar topology to osmotin. It is believed that the β-sandwich structure attaches to the membrane, while a three-turn α-helix lying on the surface of the β-sheet may be involved in membrane pore formation, possibly by the penetration of the membrane by the helix.Interestingly, this entry also includes bryoporin from the moss Physcomitrella patens. It shares the protein structure similarity with sea anemone actinoporin. The bryoporin gene was upregulated by various abiotic stresses, in particular most strongly by dehydration stress. Overexpression of the bryoporin gene heightens drought tolerance in P. patens significantly [ ]. | Name | Sea anemone actinoporin-like |
| Short Name | Anemon_actinoporin-like | Type | Family |
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