Identification of the histidine residues of hemopexin that coordinate with heme-iron and of a receptor-binding region.
J Biol Chem
; 268(9): 6256-62, 1993 Mar 25.
Article
em En
| MEDLINE
| ID: mdl-7681064
ABSTRACT
Rabbit hemopexin cDNA was cloned from a rabbit liver lambda gt11 cDNA expression library using a mixture of five monoclonal antibodies raised against rabbit hemopexin, and the entire rabbit hemopexin sequence was determined. The heme-binding domain I of rabbit hemopexin (Smith, A., and Morgan, W. T. (1984) J. Biol. Chem. 259, 12049-12053) contains only 4 histidine residues which are conserved in rabbit, human, rat, and mouse hemopexin. The 2 axial heme-iron coordinating histidine residues, identified by Edman microsequencing and amino acid analyses of chemically modified domain I and isolated fragments of domain I, are the conserved histidine residues at positions 56 and 127 of the mature rabbit protein. The epitope recognized by JEN-14 (a monoclonal antibody which specifically reacts with domain I and blocks the hemopexin-receptor interaction (Morgan, W. T., Muster, P., Tatum, F. M., McConnell, J., Conway, T. P., Hensley, P., and Smith, A. (1988) J. Biol. Chem. 263, 8220-8225) was shown to lie between residues 122 and 142 by Western blotting of protease-digested domain I and transposon-insertion mutants of domain I expressed in a plasmid vector system. The location of this epitope near the heme-binding histidine residue 127 is compatible with a transport mechanism in which the release of heme from hemopexin is accompanied by a concomitant transfer of heme to the hemopexin receptor or the membrane heme-binding protein (Smith, A., and Morgan, W. T. (1985) J. Biol. Chem. 260, 8325-8329).
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Hemopexina
/
Receptores de Peptídeos
/
Receptores de Superfície Celular
/
Heme
/
Histidina
/
Ferro
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1993
Tipo de documento:
Article