title: Rat natural killer cell antigen, NKR-P1, related to C-type animal lectins is a carbohydrate-binding protein.
abstract: Natural killer receptor protein 1 (NKR-P1, a family of proteins), which is a dimeric transmembrane protein predominantly on rat and murine natural killer cells, contains an extracellular motif related to calcium-dependent animal lectins. The domain architecture of this protein and the finding that its cross-linking with antibody results in activation of natural killer cells make it a promising candidate for a receptor function. We have expressed a full-length NKR-P1 protein of the rat in COS cells and prepared soluble extracellular fragments by controlled proteolysis or by expression of truncated cDNA in bacteria. Dimerization of soluble NKR-P1 is predominantly dependent on the presence of an intact juxta-membrane stalk region and independent of N-glycosylation. Binding and inhibition studies using monosaccharides and neoglycoconjugates indicate that NKR-P1 is a lectin with a preference order of GalNAc > GlcNAc >> Fuc >> Gal > Man. At neutral pH, Ca2+ is tightly associated with the protein such that only a proportion can be removed by 10 mM EGTA. However, NKR-P1 can be decalcified completely at pH 10 with a total loss of carbohydrate binding. After recalcification at pH 8, carbohydrate binding is completely restored. Thus, NKR-P1 differs from other calcium-dependent animal lectins investigated so far in its pattern of monosaccharide recognition and in the tightness of Ca2+ binding.
authors.affiliation: Institute of Biotechnology, Charles University Prague, Czech Republic.
authors.forename: K
authors.initials: K
authors.lastname: Bezouska
authors.forename: G
authors.initials: G
authors.lastname: Vlahas
authors.forename: O
authors.initials: O
authors.lastname: Horváth
authors.forename: G
authors.initials: G
authors.lastname: Jinochová
authors.forename: A
authors.initials: A
authors.lastname: Fiserová
authors.forename: R
authors.initials: R
authors.lastname: Giorda
authors.forename: W H
authors.initials: WH
authors.lastname: Chambers
authors.forename: T
authors.initials: T
authors.lastname: Feizi
authors.forename: M
authors.initials: M
authors.lastname: Pospísil
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D002522:Chlorocebus aethiops; D002850:Chromatography, Gel; D003001:Cloning, Molecular; D007668:Kidney; D007694:Killer Cells, Natural / Q000276:immunology*; D007700:Kinetics; D037102:Lectins / Q000378:metabolism*; D037181:Lectins, C-Type; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009005:Monosaccharides / Q000378:metabolism*; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D000954:Antigens, Surface; D037102:Lectins; D037181:Lectins, C-Type; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D009005:Monosaccharides; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011994:Recombinant Proteins; D002118:Calcium