Nitrophorins: Lipocalin-based heme proteins transporting nitric oxide

Paolo Ascenzi, Marco Nardini, Martino Bolognesi, William R. Montfort

Research output: Contribution to journalReview articlepeer-review

15 Scopus citations


Nitrophorins 1-4 (NPs; NP1 to NP4) are salivary heme proteins secreted from the blood-sucking insect Rhodnius prolixus. NPs transfer nitric oxide (NO) to the victim, resulting in vasodilatation, sequester histamine, reducing host inflammation and immune response, and inhibit blood coagulation. The NP fold is based on an eight-stranded antiparallel β-barrel, typically observed in the lipocalin homology family, which hosts a heme group. Although NPs use the ferric heme to bind NO and histamine, they are unrelated to the six/eight α-helix (non)vertebrate hemoglobins, which bind NO preferentially to the ferrous heme, but do not bind histamine. Therefore, NPs and hemoglobins can be considered as an evolutionary experiment, where the heme group has been adapted to structurally different protein families to achieve similar function(s).

Original languageEnglish (US)
Pages (from-to)68-71
Number of pages4
JournalBiochemistry and Molecular Biology Education
Issue number1
StatePublished - Jan 2002


  • Anticoagulation activity
  • Heme protein
  • Hemoglobin
  • Histamine sequestering
  • Lipocalin
  • Nitric oxide storage
  • Nitric oxide transport
  • Nitrophorin

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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