PROSITE documentation PDOC00023
Hemopexin domain signature and hemopexin repeat profile


Hemopexin is a serum glycoprotein that binds heme and transports it to the liver for breakdown and iron recovery, after which the free hemopexin returns to the circulation. Structurally hemopexin consists of two similar halves of approximately two hundred amino acid residues connected by a histidine-rich hinge region. Each half is itself formed by the repetition of a basic unit of some 35 to 45 residues. Hemopexin-like domains have been found [1,2] in two other types of proteins:

  • In vitronectin (also known as complement S protein and serum spreading factor), a multifunctional adhesion glycoprotein that is present abundantly in plasma and the extracellular matrix. Vitronectin consists of an N- terminal somatomedin B (see <PDOC00453>) and, like hemopexin, two hemopexin-like domains [3].
  • In most members of the matrix metalloproteinases family (matrixins) (see <PDOC00129>): MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-11, MMP-12, MMP-13, MMP-14, MMP-15, MMP-16, MMP-17, MMP-18, MMP-19, MMP-20, MMP-24, and MMP-25. These zinc endoproteases have a single hemopexin-like domain in their C-terminal section [4].

It is suggested that the hemopexin domain facilitates binding to a variety of molecules and proteins.

The hemopexin domain exhibits the shape of an oblate ellipsoidal disk. The polypeptide chain is organized in four β-sheet (blades) I to IV, which are almost symmetrically arranged around a central axis in consecutive order, giving rise to the formation of a four-bladed propeller (see <PDB:1PEX>). Each propeller blade or repeat is made up of four antiparallel β-strands connected in a W-like strand topology, and is strongly twisted [5,6].

We developed both a pattern and a profile. The signature pattern for the hemopexin domain has been derived from the best conserved region which is located at the beginning of the second repeat. The profile covers the entire hemopexin repeat.

Last update:

May 2013 / Text revised; profile added.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

HEMOPEXIN_2, PS51642; Hemopexin repeat profile  (MATRIX)

HEMOPEXIN, PS00024; Hemopexin domain signature  (PATTERN)


1AuthorsHunt L.T. Barker W.C. Chen H.R.
TitleA domain structure common to hemopexin, vitronectin, interstitial collagenase, and a collagenase homolog.
SourceProtein Seq. Data Anal. 1:21-26(1987).
PubMed ID2451821

2AuthorsStanley K.K.
TitleHomology with hemopexin suggests a possible scavenging function for S-protein/vitronectin.
SourceFEBS Lett. 199:249-253(1986).
PubMed ID2422056

3AuthorsMarioli D.J. Zarkadis I.K.
TitleThe vitronectin gene in rainbow trout: cloning, expression and phylogenetic analysis.
SourceFish Shellfish Immunol. 24:18-25(2008).
PubMed ID17981477

4AuthorsPiccard H. Van den Steen P.E. Opdenakker G.
TitleHemopexin domains as multifunctional liganding modules in matrix metalloproteinases and other proteins.
SourceJ. Leukoc. Biol. 81:870-892(2007).
PubMed ID17185359

5AuthorsGomis-Rueth F.X. Gohlke U. Betz M. Knaeuper V. Murphy G. Lopez-Otin C. Bode W.
TitleThe helping hand of collagenase-3 (MMP-13): 2.7 A crystal structure of its C-terminal haemopexin-like domain.
SourceJ. Mol. Biol. 264:556-566(1996).
PubMed ID8969305

6AuthorsGaur V. Qureshi I.A. Singh A. Chanana V. Salunke D.M.
TitleCrystal structure and functional insights of hemopexin fold protein from grass pea.
SourcePlant Physiol. 152:1842-1850(2010).
PubMed ID20147493

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