InterPro : IPR002351

Name  Nitrophorin domain Short Name  Nitrophorin_domain
Type  Domain Description  Nitrophorins are haemoproteins found in saliva of blood-feeding insects [, ]. Saliva of the blood-sucking bug Rhodnius prolixus(Triatomid bug) contains four homologous nitrophorins, designated NP1 to NP4 in order of their relative abundance in the glands []. As isolated, nitrophorins contain nitric oxide (NO) ligated to the ferric (FeIII) haem iron. Histamine, which is releasedby the host in response to tissue damage, is another nitrophorin ligand. Nitrophorins transport NO to the feeding site.Dilution, binding of histamine and increase in pH (from pH ~5 in salivary gland to pH ~7.4 in the host tissue) facilitate the release of NO into the tissue where it induces vasodilatation.The salivary nitrophorin from the hemipteran Cimex lectularius(Bed bug) has no sequence similarity to R. prolixus nitrophorins. It is suggested that the two classes of insect nitrophorins have arisen as a product of the convergentevolution [].3-D structures of several nitrophorin complexes are known []. The nitrophorin structures reveal lipocalin-likeeight-stranded beta-barrel, three alpha-helices and two disulphide bonds, with haem inserted into one end of the barrel. Members of the lipocalin family are known to bind a variety of small hydrophobic ligands, including biliverdin, in a similar fashion (see []for review). The haem iron is ligated to His59. The position of His59 is restrained through water-mediatedhydrogen bond to the carboxylate of Asp70. The His59-Fe bond is bent ~15 degrees out of the imidazole plane. Asp70 forms an unusual hydrogen bond with one of the haem propionates, suggesting the residue has an altered pKa. In NP1-histaminestructure, the planes of His59 and histamine imidazole rings lie in an arrangement almost identical to that found in oxidised cytochrome b5.This entry represents the nitrophorin structural domain.

Sequence Features

GO Displayer


InterPro protein domain ID --> Contigs



0 Child Features

0 Contains

0 Found In

1 Parent Features

Id Name Short Name Type
IPR012674 Calycin Calycin Domain

5 Publications

First Author Title Year Journal Volume Pages
Flower DR The lipocalin protein family: structure and function. 1996 Biochem J 318 ( Pt 1) 1-14
Walker FA Novel nitric oxide-liberating heme proteins from the saliva of bloodsucking insects. 1999 Met Ions Biol Syst 36 621-63
Montfort WR Nitrophorins and related antihemostatic lipocalins from Rhodnius prolixus and other blood-sucking arthropods. 2000 Biochim Biophys Acta 1482 110-8
Champagne DE Purification, partial characterization, and cloning of nitric oxide-carrying heme proteins (nitrophorins) from salivary glands of the blood-sucking insect Rhodnius prolixus. 1995 J Biol Chem 270 8691-5
Valenzuela JG Purification and cloning of the salivary nitrophorin from the hemipteran Cimex lectularius. 1998 J Exp Biol 201 2659-64

To cite PlanMine, please refer to the following publication:

Rozanski, A., Moon, H., Brandl, H., Martín-Durán, J. M., Grohme, M., Hüttner, K., Bartscherer, K., Henry, I., & Rink, J. C.
PlanMine 3.0—improvements to a mineable resource of flatworm biology and biodiversity
Nucleic Acids Research, gky1070. doi:10.1093/nar/gky1070 (2018)