![Figure 4. Species-specific sequence changes in the emergent EA and EB epitope regions of the α3(IV)NC1 domain. (A) Alignment of epitopes and EA and EB of Danio rerio, chicken, and human. The 6 variable (nonscaffold) residues of epitope EA and the 5 variable (nonscaffold) residues of EB are numbered. The color coding of residues (which is identical to that in panels B-D) denotes the chemical properties of residues, and is explained in the colored key at right. The numbered keys delineate the emergence of these epitopes as they arose from immunonegative Danio rerio to immunopositive chicken and human by defining the evolutionarily induced changes in chemical properties and their effects on Goodpasture autoantibody binding. (B-G) Using the known [(α1)2α2]2 NC1 hexamer crystal structure (PDB ID 1LI1), we have modeled the species-specific amino acids in the EA and EB regions for Danio rerio (B,E), chicken (C, F) and human (D,G) onto a α3(IV)NC1 backbone-homology structure. (B-D) The molecular surface and amino acid character of nonconserved residues in both the EA and EB epitope regions for Danio rerio (B), chicken (C), and human (D) are rendered in a color-coded, semitransparent surface representation: neutral (gray), strongly hydrophilic (green), moderately hydrophilic (cyan), basic (blue), and acidic (red) amino acid character. The remainder of the α3(IV)NC1 domain backbone is shown in ribbon representation (gray). (E-G) The peptide backbone from residues 17-31 (using human α3(IV) numbering) in the α3(IV) chain corresponding to the EA epitope region is colored blue, and from residues 127-141 corresponding to the EB epitope region is colored green. Nonconserved residues in EA and EB are shown with rendered side chains, and identified by single-letter residue code. Sequence differences between the Danio rerio and chicken EA and EB epitopes are highlighted in yellow on the chicken homology α3(IV)NC1 domain structure. Additionally, sequence differences between the chicken and human EA and EB epitope regions are highlighted further in red on the human homology α3(IV)NC1 domain structure. The Q57 critical in forming the conformational, discontinuous epitope EA is colored magenta.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/107/5/10.1182_blood-2005-05-1814/2/zh80050691760004.jpeg?Expires=1735826641&Signature=QFznkT68TId2l5BXXWB8FMlbAeN2Kn28hsdENIR8NyLQPnQm2jbFRCPWEhLk91JcIn-tBNyG~YWciT1eAHZbKA~IpyU43u3HglRbAAlyETwVLLQqU1B7-PVcVDzWxsTZjYi7SIz40SNrbqOpr9wFdGSmR7gCEWoDOAS8PyTdClLiSEBh25C017bj06APdctyER716cYTCRgD45CWUOKmkPsii0EMHMMGRWgg5vB0V7MAd2nwKAFq76T5Y-vVcJp-RAGaITKpZkUuujD1ey-ML6WI3Ub5WcJg8klWbYketooEXH1fTZNOwJVILzLUozfnajVn4h7TlXLZ10A~6Tb4Pw__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Species-specific sequence changes in the emergent EA and EB epitope regions of the α3(IV)NC1 domain. (A) Alignment of epitopes and EA and EB of Danio rerio, chicken, and human. The 6 variable (nonscaffold) residues of epitope EA and the 5 variable (nonscaffold) residues of EB are numbered. The color coding of residues (which is identical to that in panels B-D) denotes the chemical properties of residues, and is explained in the colored key at right. The numbered keys delineate the emergence of these epitopes as they arose from immunonegative Danio rerio to immunopositive chicken and human by defining the evolutionarily induced changes in chemical properties and their effects on Goodpasture autoantibody binding. (B-G) Using the known [(α1)2α2]2 NC1 hexamer crystal structure (PDB ID 1LI1), we have modeled the species-specific amino acids in the EA and EB regions for Danio rerio (B,E), chicken (C, F) and human (D,G) onto a α3(IV)NC1 backbone-homology structure. (B-D) The molecular surface and amino acid character of nonconserved residues in both the EA and EB epitope regions for Danio rerio (B), chicken (C), and human (D) are rendered in a color-coded, semitransparent surface representation: neutral (gray), strongly hydrophilic (green), moderately hydrophilic (cyan), basic (blue), and acidic (red) amino acid character. The remainder of the α3(IV)NC1 domain backbone is shown in ribbon representation (gray). (E-G) The peptide backbone from residues 17-31 (using human α3(IV) numbering) in the α3(IV) chain corresponding to the EA epitope region is colored blue, and from residues 127-141 corresponding to the EB epitope region is colored green. Nonconserved residues in EA and EB are shown with rendered side chains, and identified by single-letter residue code. Sequence differences between the Danio rerio and chicken EA and EB epitopes are highlighted in yellow on the chicken homology α3(IV)NC1 domain structure. Additionally, sequence differences between the chicken and human EA and EB epitope regions are highlighted further in red on the human homology α3(IV)NC1 domain structure. The Q57 critical in forming the conformational, discontinuous epitope EA is colored magenta.
