Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antisera were raised in rabbits against histamine conjugated to human serum albumin (HSA) by the carbodiimide (ECDI) method. The specificity of the antisera was studied in a radioimmunoassay using 125I-protein A for detection of IgG binding. The HIS-HSA antisera reacted with histamine-HSA conjugates prepared by either the carbodiimide or diisocyanate coupling procedure, as well as with carbodiimide-prepared histamine-ferritin and histamine-ovalbumin conjugates. On the contrary, the antisera were unreactive with unconjugated HSA, ECDI-reacted HSA, or HSA conjugated to ethanolamine or pentylamine. Free unconjugated histamine significantly inhibited antibody binding to histamine-HSA and 50% inhibition of antibody binding (IC50) was recorded at 3 mM histamine concn. On a histamine molar concn basis a much lower inhibitory potency of free histamine was recorded, as compared to histamine-protein conjugates (IC50 = 3 X 10(-6) mM). This probably reflected amplification of antibody binding to the multivalent ligand, but possibly also that the protein carrier adds some common features to the antigenic determinant. Histidine, ornithine, glutamine, asparagine, sterylamine and several other amino acids lacked inhibitory effects. Histamine H1 and H2 receptor antagonists inhibited histamine binding to the histamine antibodies. The antagonists varied in their affinity for the histamine antibodies and 50% inhibition of antibody binding was recorded in the range of 1-50 mM concn of the antagonists. Comparing one H1 and one H2 antagonist (diphenhydramine and cimetidine, respectively) two of the sera were preferentially inhibited by cimetidine whereas the third serum seemed to be more prone to inhibition by diphenhydramine.
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PMID:Production and characterization of rabbit antibodies against histamine. 379 25

Histamine covalently bound to glutaraldehyde-activated ferritin was prepared as either monomers or as small aggregates of approximately 0.05 to 0.15 micrometer Diam, suitable for electron microscopic detection of histamine cellular binding sites. The histamine-ferritin conjugates (MF) maintain the histamine capability to induce the opening of endothelial junctions in venules. To investigate the distribution of histamine receptors in the vascular endothelium, monomers or aggregates of MF were perfused in situ (mice), and various vascular beds, particularly that of the diaphragm, were fixed and processed for electron microscopy. The conjugate was preferentially bound on restricted areas of luminal endothelial cell plasmalemma especially in regions rich in filaments, and near the junctions between endothelial cells. The density of histamine binding sites was characteristically high in venules; it occurred to a much lesser extent in arterioles, veins, and muscular arteries whereas capillaries and aorta showed the lowest values. A similar distribution was obtained after perfusion of H1 or H2 receptor agonists coupled to ferritin (2-pyridylethylamine-ferritin [PF], or 4-methylhistamine-ferritin [MF], respectively). The binding specificity was assessed through control experiments with either native or activated ferritin or by competition with histamine. The findings suggest that histamine receptors are largely represented in the cell membrane of the vascular endothelium, particularly in venules. Experiments using specific H1 and H2 receptor agonists (PF and MF) and antagonists (mepyramine and cimetidine) indicate that the venular endothelium contains mainly H2 receptors.
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PMID:Histamine receptors of the microvascular endothelium revealed in situ with a histamine-ferritin conjugate: characteristic high-affinity binding sites in venules. 720 74