Tick histamine-binding proteins: lipocalins with a second binding cavity.
Biochim Biophys Acta
; 1482(1-2): 92-101, 2000 Oct 18.
Article
en En
| MEDLINE
| ID: mdl-11058751
ABSTRACT
Tick histamine-binding proteins (HBPs) are lipocalins with two binding pockets. One of these binds histamine with a high affinity and is found at the position expected from other lipocalins, adjacent to the omega-loop at the open-end of the beta-barrel. A second binding cavity, which is a low-affinity site for histamine in one of the HBPs, is located at the end of the barrel that is closed off in other lipocalins. In order to create the second site, the 'closed-end' region has undergone a major reconstruction. Typical lipocalin characteristics, such as the 3(10) helix and a structural cluster of highly conserved residues, have been lost, while an alpha-helix now shields the cavity from the exterior. The prominence of acidic residues in the binding pockets is another distinctive characteristic of HBPs. Whereas most lipocalins have highly hydrophobic binding cavities designed to bind lipophilic compounds, HBPs have evolved to trap cationic, hydrophilic molecules.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Receptores Histamínicos H1
/
Receptores Histamínicos H2
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Biochim Biophys Acta
Año:
2000
Tipo del documento:
Article
País de afiliación:
Reino Unido