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Limulus factor D, a 43‐kDa protein isolated from horseshoe crab hemocytes, is a serine protease homologue with antimicrobial activity
Author(s) -
Kawabata Shun-ichiro,
Tokunaga Fuminori,
Kugi Yoshie,
Motoyama Shiho,
Miura Yoshiki,
Hirata Michimasa,
Iwanaga Sadaaki
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01224-0
Subject(s) - limulus , peptide sequence , serine protease , biology , horseshoe crab , complementary dna , biochemistry , microbiology and biotechnology , proteases , signal peptide , virulence factor , amino acid , protease , enzyme , gene , paleontology , virulence
A glycoprotein ( M r = 43 000) from horseshoe crab hemocytes with antimicrobial activity against Gram‐negative bacteria was purified. The internal peptide sequences coincided exactly with the deduced amino acid sequence of a cDNA clone, designated limulus factor D, which was isolated by screening a hemocyte cDNA library with an anti‐human plasminogen antibody. The open reading frame codes for a precursor of factor D of 394 amino acid residues, including an NH 2 ‐terminal signal sequence. The COOH‐terminal domain of factor D has significant sequence homology with the catalytic domain of mammalian serine proteases, in particular with human tissue plasminogen activator (32% identity), except for the substitution of Ser of the active site triad to Gly. Factor D has a unique NH 2 ‐terminal domain with weak sequence homology with part of the mammalian interleukin‐6 receptor α‐chain. Factor D is likely to have an important role in host defense mechanisms.