Crystal structure of hemolin: a horseshoe shape with implications for homophilic adhesion.
Hemolin, an insect immunoglobulin superfamily member, is a lipopolysaccharide-binding immune protein induced during bacterial infection. The 3.1 angstrom crystal structure reveals a bound phosphate and patches of positive charge, which may represent the lipopolysaccharide binding site, and a new and unexpected arrangement of four immunoglobulin-like domains forming a horseshoe. Sequence analysis and analytical ultracentrifugation suggest that the domain arrangement is a feature of the L1 family of neural cell adhesion molecules related to hemolin. These results are relevant to interpretation of human L1 mutations in neurological diseases and suggest a domain swapping model for how L1 family proteins mediate homophilic adhesion.
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Division of Biology 156-29 and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.
Gastinel
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Vaughn
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Faye
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Poon
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Bjorkman
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D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D015816:Cell Adhesion Molecules, Neuronal / Q000737:chemistry; D018360:Crystallography, X-Ray; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D006801:Humans; D007136:Immunoglobulins; D019476:Insect Proteins; D039841:Leukocyte L1 Antigen Complex; D008562:Membrane Glycoproteins / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009036:Moths; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D015816:Cell Adhesion Molecules, Neuronal; D029721:Drosophila Proteins; D007136:Immunoglobulins; D019476:Insect Proteins; D039841:Leukocyte L1 Antigen Complex; D008562:Membrane Glycoproteins; D019006:Neural Cell Adhesion Molecules; D011506:Proteins; D011994:Recombinant Proteins; C061745:Nrg protein, Drosophila; C066846:hemolin