Characterization of an IL-1 receptor from Asterias forbesi coelomocytes.
The tremendous importance of cytokines to immune defensive systems suggests that they have been conserved through evolution. The existence of interleukin (IL)-1-like molecules in several invertebrate groups substantiates this hypothesis. To characterize further the relationship of invertebrate IL-1-like molecules, we have used competitive binding assays to show that invertebrate coelomocytes of the starfish Asterias forbesi possess an IL-1-specific binding protein. Competitive binding experiments used radiolabeled human IL-1alpha. IL-1 bound specifically to the coelomocytes by a single high-affinity binding site (K(d) = 8.72 x 10(-10)/M). There are approximately 6000 binding sites per cell. The specificity of the receptor was confirmed by demonstrating that, among a group of cytokines and lymphokines tested, only vertebrate IL-1- or echinoderm IL-1-like molecules and the vertebrate IL-1 receptor antagonist inhibit IL-1 binding. Treatment of coelomocytes (labeled with IL-1alpha) with bivalent water-soluble crosslinkers identified a membrane protein of approximately 70 kDa to which IL-1 is specifically crosslinked.
Department of Biology, University of Massachusetts at Boston, Boston, Massachusetts 02125-3393, USA.
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D000818:Animals; D001667:Binding, Competitive; D002469:Cell Separation; D003432:Cross-Linking Reagents; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D017472:Receptors, Interleukin-1 / Q000302:isolation & purification*; D013215:Starfish / Q000166:cytology* / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D003432:Cross-Linking Reagents; D007375:Interleukin-1; D007376:Interleukin-2; D015850:Interleukin-6; D017472:Receptors, Interleukin-1; D014409:Tumor Necrosis Factor-alpha