The loop region around amino acid residue 50, the N-terminal part of the alpha-helix, and the C-terminus of human retinol-binding protein are not located in or close to the transthyretin binding site.
Although the three-dimensional structures of both human retinol-binding protein (RBP) and transthyretin (TTR) are known, the binding sites have not been defined. In this study we have epitope-mapped a rabbit antiserum against human RBP using synthetic peptides corresponding to all potentially antigenic sites. Immunoreactivity was seen with peptides corresponding to amino acid residues 46-54, 137-146, 143-153, and 172-182 of RBP. Since previous studies have demonstrated that these antibodies bind equally well to free RBP and to the RBP-TTR complex, we conclude that neither the loop region around amino acid residue 50, the N-terminal part of the alpha-helix, nor the C-terminus of RBP is located in or close to the TTR binding site. Our results support the hypothesis that one of the entrance loops is involved in the TTR binding.
Melhus
H
H
Department of Internal Medicine, University Hospital, Uppsala, Sweden.
Rask
L
L
D000818:Animals; D018604:Epitope Mapping; D006801:Humans; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D011817:Rabbits; D051381:Rats; D017457:Receptors, Albumin / Q000737:chemistry*; D012177:Retinol-Binding Proteins / Q000737:chemistry*
D017457:Receptors, Albumin; D012177:Retinol-Binding Proteins; C091986:transthyretin receptor