title: Identification of a beta 2 (CD18) molecule in a teleost species, Ictalurus punctatus Rafinesque.
abstract: Beta 2, in combination with the alpha subunit, is responsible for tight adhesion of leukocytes, especially neutrophils and macrophages, in areas of inflammation. Although identified in mammalian and avian species; the beta 2 or CD18 molecule has yet to be identified in fish. The present investigation has identified a full-length channel catfish, Ictalurus punctatus, cDNA beta 2 molecule composed of 2.8 kb and a deduced amino acid sequence of 772 amino acids. The catfish molecule has an amino acid homology ranging from 54 to 63% with mouse, bovine, rabbit, human and chicken. The channel catfish molecule retains several characteristics of mammalian beta 2 molecules, such as cysteine-rich repeat regions, N-linked glycosylation sites, and several proposed signal sequences. Expression of the beta 2 molecule on the catfish neutrophil cytoplasmic membranes is increased upon phorbol dibutyrate stimulation of the cells. Based on Western blotting and the immunoprecipitation test, the channel catfish beta 2 molecule has a molecular mass of approximately 95 kD, essentially the same as that for mammalian species. However, two additional molecules, perhaps alpha chains, of unexpected molecular mass appear to co-precipitate in the SPIT with the 95 kD CD18 molecule. These results confirm the existence and expression of a beta 2 gene in channel catfish, a species phylogenetically distant from mammalian species.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina, Chapel Hill 27599, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Qian
authors.forename: A J
authors.initials: AJ
authors.lastname: Ainsworth
authors.forename: M
authors.initials: M
authors.lastname: Noya
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D018821:CD18 Antigens / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D002417:Cattle; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005434:Flow Cytometry; D006801:Humans; D007059:Ictaluridae / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D018821:CD18 Antigens; D018076:DNA, Complementary