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Haptoglobin, a hemoglobin-binding plasma protein, is present in bony fish and mammals but not in frog and chicken

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  • Document Type:
    Electronic Resource
  • Online Access:
    Proceedings of the National Academy of Sciences of the United States of America, 0027-8424, 2006, 103:11, s. 4168-4173
  • Additional Information
    • Publisher Information:
      Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi 2006
    • Added Details:
      Wicher, Krzysztof B
      Fries, Erik
    • Abstract:
      Hemoglobin (Hb) released from erythrocytes may cause oxidation of lipids and proteins. Haptoglobin (Hp), which occurs in the plasma of all mammals, binds free Hb and inhibits its oxidative activity. It is not known whether this protective protein also exists in lower vertebrates. By analyzing available genomic sequences, we have found that bony fish, but not more primitive animals, have a gene coding for a protein homologous to mammalian Hp. Furthermore, we show that this protein is present in the plasma of Japanese pufferfish (Takifugu rubripes) and that it binds Hb. These results, together with a phylogenetic analysis, suggest that Hp evolved from a complement-associated protein (mannose-binding lectin-associated serine proteinase, MASP), with the emergence of fish. Surprisingly, we found that both chicken (Gallus gallus) and the Western clawed frog (Xenopus tropicalis) lack the Hp gene. In chicken plasma, however, we identified a different type of Hb-binding protein, PIT54, which has been reported to be a potent antioxidant. PIT54 is a soluble member of the family of scavenger receptor cysteine-rich proteins, and we found that its gene exists only in birds. We also show that the plasma of ostrich (Strutio camelus), a primitive bird, contains both PIT54 and Hp. Collectively, our data suggest that PIT54 has successively taken over the function of Hp during the evolution of the avian lineage and has completely replaced the latter protein in chicken.
    • Subject Terms:
    • Accession Number:
    • Availability:
      Open access content. Open access content
    • Note:
    • Other Numbers:
      PMID 16537503
    • Contributing Source:
      From OAIster®, provided by the OCLC Cooperative.
    • Accession Number: