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J. Biol. Chem., Vol. 281, Issue 42, 31553-31561, October 20, 2006
The First Structure from the SOUL/HBP Family of Heme-binding Proteins, Murine P22HBP*![]() ![]() ![]()
From the
Murine p22HBP, a 22-kDa monomer originally identified as a cytosolic heme-binding protein ubiquitously expressed in various tissues, has 27% sequence identity to murine SOUL, a heme-binding hexamer specifically expressed in the retina. In contrast to murine SOUL, which binds one heme per subunit via coordination of the Fe(III)-heme to a histidine, murine p22HBP binds one heme molecule per subunit with no specific axial ligand coordination of the Fe(III)-heme. Using intrinsic protein fluorescence quenching, the values for the dissociation constants of p22HBP for hemin and protoporphyrin-IX were determined to be in the low nanomolar range. The three-dimensional structure of murine p22HBP, the first for a protein from the SOUL/HBP family, was determined by NMR methods to consist of a 9-stranded distorted
Received for publication, June 22, 2006 , and in revised form, August 10, 2006. The atomic coordinates and structure factors (code 2GOV) have been deposited in the Protein Data Bank, Research Collaboratory for Structural Bioinformatics, Rutgers University, New Brunswick, NJ (http://www.rcsb.org/). * This work was supported by the Fundação para a Ciência e Tecnologia, Programa Operacional Ciência, Tecnologia, Inovação (POCTI), and Fundo Europeu de Desenvolvimento Regional in Portugal (Grant SFRH/BD/3091/2000 to J. S. D. and Grant POCTI/BME/39184/2001 to B. J. G. and A. L. M.) and National Institutes of Health Grants GM64598 (to B. F. V.) and DK63191 (to G. C. F.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1 To whom correspondence should be addressed. Tel.: 351-234-401-506; Fax: 351-234-370-084; E-mail: brian.goodfellow{at}dq.ua.pt.
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