1HXN | pdb_00001hxn

1.8 A crystal structure of the C-terminal domain of rabbit serum haemopexin.

(1995) Structure 3: 551-559

• PubMed: 8590016 Search on PubMed
• DOI: https://doi.org/10.1016/s0969-2126(01)00189-7
• Primary Citation of Related Structures:  
  1HXN


• PubMed Abstract: 
  

  Haemopexin is a serum glycoprotein that binds haem reversibly and delivers it to the liver where it is taken up by receptor-mediated endocytosis. Haemopexin has two homologous domains, each having a characteristic fourfold internal sequence repeat. Haemopexin-type domains are also found in other proteins, including the serum adhesion protein vitronectin and various collagenases, in which they mediate protein-protein interactions. We have determined the crystal structure of the C-terminal domain of haemopexin at 1.8 A resolution. The domain is folded into four beta-leaflet modules, arranged in succession around a central pseudo-fourfold axis. A funnel-shaped tunnel through the centre of this disc-shaped domain serves as an ion-binding site. A model for haem binding by haemopexin is proposed, utilizing an anion-binding site at the wider end of the central tunnel, together with an associated cleft. This parallels the active-site location in other beta-propeller structures. The capacity to bind both cations and anions, together with the disc shape of the domain, suggests that such domains may be used widely for macromolecular recognition.

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Organizational Affiliation: 
• Department of Chemistry and Biochemistry, Massey University, Palmerston North, New Zealand.