Isolation, cDNA cloning, and characterization of an 18-kDa hemagglutinin and amebocyte aggregation factor from Limulus polyphemus.

摘要: An 18-kDa hemagglutinin which possesses the property of inducing both aggregation amebocytes and agglutination erythrocytes has been isolated from Limulus polyphemus purified by ion exchange chromatography. This nonglycosylated, single chain polypeptide with an M(r) 18,506 isoelectric point 8.3 is stored exclusively in large secretory granules amebocytes. Based on partial N-terminal amino acid sequence 63 residues, DNA probes have synthesized for screening a pBR322 cDNA library constructed The coding this protein reveals presence 19-residue signal peptide preceding 153-residue open reading frame. Northern blot analysis indicates mRNA species. primary structure derived corresponding internal homology consisting two consensus sequences, Val-Asn-Asp/Ser-Trp-Asp Glu-Asp-Arg-Arg-Trp. formation 5 disulfide bonds between 10 half-cysteines divides molecule into three looped domains each containing Glu-Asp-Arg-Arg-Trp repeating unit. One novel features that it shares 37% identity 22-kDa mammalian extracellular matrix fetal bovine skin (Neame, P.J., Choi, H.U., Rosenberg, L.C. (1989) J. Biol. Chem. 264, 5474-5479). proteins exhibit similar pattern domains, domain homologous (i.e. Glu-Asp-Arg-Arg-Trp). overall seems to be highly related, exception tyrosine-rich region present only protein. functional properties are agglutinates horse aggregates amebocytes, effective adhesion promoter dermal fibroblasts. On basis these unique properties, newly characterized termed 18K agglutination-aggregation factor (18K-LAF).