title: cDNA cloning, tissue distribution, and subcellular localization of horseshoe crab big defensin.
abstract: A full-length cDNA for horseshoe crab big defensin with a strong antimicrobial activity was obtained from a hemocyte cDNA library. The open reading frame of the cDNA coded for an NH2-terminal signal sequence followed by a propeptide and the mature big defensin. The propeptide is linked to the mature protein through an -Arg-X-Lys/Arg-Arg- motif, the processing site for Kex2-like proteases. Northern blot analysis revealed that big defensin is expressed in all the tissues tested, suggesting that big defensin plays an important role not only in hemocytes but also in other tissues for host defense. The subcellular localization, determined by immunocytochemistry at ultrastructural level, confirmed the previous findings obtained by biochemical analysis that big defensin locates in both small and large granules in hemocytes. Big defensin is the first example to demonstrate the existence of broad tissue distribution in horseshoe crab.
authors.affiliation: Department of Biology, Faculty of Science, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kawabata
authors.forename: T
authors.initials: T
authors.lastname: Saito
authors.forename: K
authors.initials: K
authors.lastname: Saeki
authors.forename: N
authors.initials: N
authors.lastname: Okino
authors.forename: A
authors.initials: A
authors.lastname: Mizutani
authors.forename: Y
authors.initials: Y
authors.lastname: Toh
authors.forename: S
authors.initials: S
authors.lastname: Iwanaga
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001798:Blood Proteins / Q000096:biosynthesis / Q000378:metabolism* / Q000648:ultrastructure; D015152:Blotting, Northern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000096:biosynthesis; D023082:Defensins; D015723:Gene Library; D006458:Hemolymph / Q000737:chemistry / Q000378:metabolism; D006737:Horseshoe Crabs / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D013347:Subcellular Fractions / Q000378:metabolism / Q000648:ultrastructure; D014018:Tissue Distribution
chemical_list: D001798:Blood Proteins; D018076:DNA, Complementary; D023082:Defensins