GAA1 recognizes the GPI anchor attachment signals and is complexed with GP18 to form a GPI transamidase

Abstract

Crude extract was prepared from the sea anemone, Bunodosoma cavernata. The protein content of the extract was estimated to be 0.52 mg protein/ml. The extract was standardized based on the percentage inhibition of histamine-induced contraction of the guinea pig ileum, to determine the biological unit of activity (AU) of the extract. As extracts prepared on different occasions lost potency on storage, the stability of the extract was also investigated. Extracts prepared from fresh animals were about 15% more potent than those prepared from freeze-dried animals. However, freeze-dried animal extracts maintained their potency for about 6 months under storage at −20°C. Lethality studies gave an ld50 of 40 μg protein/kg mice i.p. Also, the crude extract dose-dependently hemolyzed human erythrocytes at room temperature. This activity was favoured by higher temperatures, which peaked at about 60°C, and by pH in the alkaline range. We conclude that the crude extract from B. cavernata, though highly toxic, may also contain some biologically active agents which include a haemolytic factor and antihistamine(s), as indicated by its histamine-blocking action.