Ouabain-binding protein(s) from human plasma.

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  • Additional Information
    • Source:
      Publisher: Lippincott, Williams & Wilkins Country of Publication: United States NLM ID: 7906255 Publication Model: Print Cited Medium: Internet ISSN: 1524-4563 (Electronic) Linking ISSN: 0194911X NLM ISO Abbreviation: Hypertension Subsets: MEDLINE
    • Publication Information:
      Publication: : Hagerstown, MD : Lippincott, Williams & Wilkins
      Original Publication: [Dallas, Tex.] : [American Heart Association], [©1979]-
    • Subject Terms:
      Carrier Proteins/*blood ; Ouabain/*metabolism; Animals ; Antibodies, Monoclonal/metabolism ; Blotting, Western ; Carrier Proteins/isolation & purification ; Carrier Proteins/pharmacology ; Cattle ; Electrophoresis, Polyacrylamide Gel ; Erythrocytes/drug effects ; Erythrocytes/metabolism ; Humans ; Mice ; Mice, Inbred Strains ; Ouabain/immunology ; Protein Binding ; Rubidium Radioisotopes/pharmacokinetics ; Sepharose/metabolism ; Sodium-Potassium-Exchanging ATPase/antagonists & inhibitors ; Sodium-Potassium-Exchanging ATPase/metabolism ; gamma-Globulins/metabolism
    • Abstract:
      Conservation of the binding site on mammalian Na+,K+-ATPase for cardiac glycosides and the importance of the Na+ pump in mammalian cellular physiology has stimulated the search for a mammalian analog of these plant compounds. One candidate, isolated from brain and blood, appears to be ouabain itself or a closely related isomer, the ouabain-like compound. Little is known about the circulating form. Because human steroid hormones circulate with carrier proteins, we produced a ouabain-specific monoclonal antibody (mAb 1-10) and used it to probe normal human plasma for ouabain-protein carrier complex. Ouabain-like biological activity was isolated in association with protein bands of 80, 50, and 25 kDa. These proteins appear to be human immunoglobulins or immunoglobulin-like because they are recognized by anti-human immunoglobulin antibodies, but not by anti-mouse immunoglobulin antibodies. The protein-containing fractions inhibit the binding of mAb 1-10 to immobilized ouabain, and with further purification on protein A, the immunoglobulin-like protein binds radioactive ouabain with an IC50 of 200 to 600 nmol/L, but binds digoxin with 100-fold less affinity, suggesting specificity for ouabain or its isomer. Active protein fractions after purification on C18 inhibit Na+ pump activity in human erythrocytes (IC50 approximately 4 nmol/L, ouabain equivalents), and this chromatography appears to dissociate the ouabain-like compound from the immunoglobulin protein(s). These immunoglobulin-like molecules may represent a subset of immunoglobulins (< or =0.5% of total protein A immunoglobulin) that function as a reservoir and delivery system for ouabain-like compounds in the modulation of human Na+, K+-ATPase in vivo.
    • Grant Information:
      HL47415 United States HL NHLBI NIH HHS; R01 CA24432 United States CA NCI NIH HHS; R01 HL52282 United States HL NHLBI NIH HHS; R29AI33175 United States AI NIAID NIH HHS
    • Accession Number:
      0 (Antibodies, Monoclonal)
      0 (Carrier Proteins)
      0 (Rubidium Radioisotopes)
      0 (gamma-Globulins)
      5ACL011P69 (Ouabain)
      9012-36-6 (Sepharose)
      EC 7.2.2.13 (Sodium-Potassium-Exchanging ATPase)
    • Publication Date:
      Date Created: 20020803 Date Completed: 20020816 Latest Revision: 20191210
    • Publication Date:
      20221213
    • Accession Number:
      10.1161/01.hyp.0000027134.14160.1d
    • Accession Number:
      12154117