A common motif in proparts of Cnidarian toxins and nematocyst collagens and its putative role

In Cnidarians, cnidoblast cells contain organelles called cnidocysts, which are believed to be the product of an extremely complex regulated secretory pathway. When matured, these stinging organelles are capable of storing an d delivering toxins. We hypothesized that translated nematocyst proteins mi ght comprise specific sequences serving as signals in sorting to the organe lle. A sodium channel neurotoxin from the sea anemone Actinia equina was cl oned and the toxin precursor sequence was compared to those of nematocyst c ollagens, pore-forming toxins and ion channel neurotoxins. It was found tha t all the analyzed sequences possess a highly conserved stretch of nine ami no acid residues ending with Lys-Arg N-terminally of the mature region. (C) 2000 Elsevier Science B.V. All rights reserved.