title: The antigen receptor (NCCRP-1) on catfish and zebrafish nonspecific cytotoxic cells belongs to a new gene family characterized by an F-box-associated domain.
abstract: The catfish nonspecific cytotoxic cell receptor protein (NCCRP-1) provides an important function in target cell recognition and activation of cytotoxicity. This report identifies and characterizes a zebrafish orthologue of the catfish NCCRP-1. The zebrafish NCCRP-1 cDNA contains an open reading frame that encodes a predicted protein of 237 amino acids with a MW of 27 kDa and a pI of 5.5. Sequence similarities comparisons show that the NCCRP-1 receptors from these two phylogenetically distant species share a high degree of identity. These results suggested that NCCRP-1 performs a crucial function in innate immunity in teleosts. Further, a zebrafish 17-mer peptide corresponding to the catfish NCCRP-1 antigen-binding domain inhibited (catfish) cytotoxicity toward conventional tumor target cells (HL-60). These data appeared to indicate that the zebrafish NCCRP-1 protein may function as an antigen recognition molecule and, as such, may participate in innate immunity in teleosts. A homology search of the zebrafish NCCRP-1 protein revealed that it shares a significant level of identity with another group of proteins belonging to an F-box subfamily. These proteins share an F-box domain in the N terminus (not present in NCCRP-1) and an extremely conserved C-terminal region that has been termed the F-box-associated domain (FBA). The FBA is currently of unknown function. A new gene family is proposed in this work, based on similarities in the FBA sequences with the catfish and zebrafish NCCRP-1 peptides. This new gene family includes several F-box domain-containing proteins and a predicted C. elegans protein.
authors.affiliation: Department of Medical Microbiology and Parasitology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7386, USA. LJASO@vet.uga.edu
authors.forename: Liliana
authors.initials: L
authors.lastname: Jaso-Friedmann
authors.forename: David S
authors.initials: DS
authors.lastname: Peterson
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Gonzalez
authors.forename: Donald L
authors.initials: DL
authors.lastname: Evans
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002397:Catfishes / Q000235:genetics* / Q000276:immunology; D016384:Consensus Sequence / Q000235:genetics; D019143:Evolution, Molecular; D007694:Killer Cells, Natural / Q000276:immunology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary / Q000235:genetics; D011946:Receptors, Antigen / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015027:Zebrafish / Q000235:genetics* / Q000276:immunology
chemical_list: D011946:Receptors, Antigen; C110644:nonspecific cytotoxic cell receptor protein 1