title: Arthropod and mollusk defensins--evolution by exon-shuffling.
abstract: Arthropod and mollusk defensins are secreted antibacterial proteins that exhibit similarity in sequence, mode of action and structure and are expressed ubiquitously. Comparison of the gene organization of a newly cloned scorpion defensin gene, with that of other arthropods and the mussel, revealed that all exons and introns, aside from the exon encoding the mature protein, differ widely in number, size and sequence. This variability suggests that the exon encoding the mature defensin has undergone exon-shuffling and integrated downstream of unrelated leader sequences during evolution. Unlike other exon-shuffling events, in which modules are added into existing proteins, arthropod and mollusk defensins represent the first instance of exon-shuffling of autonomous modules.
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, Faculty of Agricultural, Food and Environmental Quality, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel. orenfroy@hotmail.com
authors.forename: Oren
authors.initials: O
authors.lastname: Froy
authors.forename: Michael
authors.initials: M
authors.lastname: Gurevitz
mesh_terms: D000818:Animals; D001181:Arthropods / Q000235:genetics*; D023082:Defensins / Q000235:genetics*; D019143:Evolution, Molecular; D005091:Exons; D015321:Gene Rearrangement; D008974:Mollusca / Q000235:genetics*
chemical_list: D023082:Defensins