The binding protein of corticotropin-releasing factor: ligand-binding site and subunit structure.
Corticotropin-releasing factor (CRF), recognized as an important stress factor, binds to a CRF receptor and a CRF-binding protein (CRFBP) that represents a reservoir of endogenous CRF. Although CRFBP was observed to dimerize, at least in part, the ligand was found to be exclusively bound to the monomer-as indicated by photoaffinity labeling. We localized the CRF binding site by using photoaffinity labeling in combination with different mass spectrometric techniques. The amino acid residues Arg-23 and Arg-36 of CRFBP were identified as the sites of photoincorporation of monofunctional and bifunctional photoprobes designed on the basis of the amino acid sequence of human/rat CRF(6-33). It was, therefore, concluded that the sequence of amino acid residues 23-36 of CRFBP is involved in ligand binding. Our data are in support of an antiparallel alignment of the photoprobe with the amino acid residues 23-36 of the CRFBP monomer.
Jahn
Olaf
O
Department of Molecular Neuroendocrinology, Max Planck Institute for Experimental Medicine, Hermann Rein Strasse 3, D-37075 Goettingen, Germany.
Eckart
Klaus
K
Brauns
Olaf
O
Tezval
Hossein
H
Spiess
Joachim
J
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003346:Corticotropin-Releasing Hormone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019920:Photoaffinity Labels; D017433:Protein Structure, Secondary; D021122:Protein Subunits; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D002352:Carrier Proteins; D008024:Ligands; D010446:Peptide Fragments; D019920:Photoaffinity Labels; D021122:Protein Subunits; D011994:Recombinant Proteins; C067133:corticotropin releasing factor-binding protein; D003346:Corticotropin-Releasing Hormone