title: Crustins: enigmatic WAP domain-containing antibacterial proteins from crustaceans.
abstract: Crustins are antibacterial proteins of ca. 7-14 kDa with a characteristic four-disulphide core-containing whey acidic protein (WAP) domain, expressed by the circulating haemocytes of crustaceans. Over 50 crustin sequences have been now reported from a variety of decapods, including crabs, lobsters, shrimp and crayfish. Three main types seem to occur but all possess a signal sequence at the amino terminus and a WAP domain at the carboxyl end. Differences between types lie in the structure of the central region. Those crustins purified as the native protein or expressed recombinantly all kill Gram-positive bacteria, and gene studies have shown that they are constitutively expressed, often at high levels, but show no consistent patterns of change in expression following injection of bacteria. This variable response to infection is enigmatic but indicates that these proteins could perform additional functions, perhaps as immune regulators in recovery from wounding, trauma or physiological stress.
authors.affiliation: Comparative Immunology Group, Gatty Marine Laboratory, University of St. Andrews, St. Andrews, Fife, Scotland KY16 8LB, UK. vjs1@st-andrews.ac.uk
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Smith
authors.forename: Jorge M O
authors.initials: JM
authors.lastname: Fernandes
authors.forename: Graham D
authors.initials: GD
authors.lastname: Kemp
authors.forename: Chris
authors.initials: C
authors.lastname: Hauton
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism*; D003445:Crustacea / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D020033:Protein Isoforms; D011506:Proteins