Antigenic mapping of human thyroglobulin--topographic relationship between antigenic regions and functional domains.
We characterized 26 mAb to human thyroglobulin to obtain a topographic map of the thyroglobulin antigenic surface. Among these mAb, three bind thyroglobulin peptides that are located in the primary sequence of thyroglobulin at either the N terminus or in the middle part of the molecule, three bind thyroglobulin via epitopes comprising the thyroid-hormone moiety, and three bind thyroglobulin through epitopes involved in the recognition of the molecule by its receptor. The 18 remaining mAb bind thyroglobulin through undetermined epitopes; most of these epitopes are resistant to trypsinization. We used two methods to map the antigenic regions of thyroglobulin: all 26 mAb were grouped, by means of cross-inhibition experiments, in 11 clusters corresponding to 11 antigenic regions of the thyroglobulin surface; by means of thyroglobulin peptides of decreasing size, obtained by time-controlled tryptic digestion, we analyzed the relative distance between pairs of epitopes in sandwich immunoassays. By combining these two methods, we organized most of the 11 antigenic regions on a topographic representation of the thyroglobulin surface. This new topographic map of thyroglobulin led us to some unexpected features of the thyroglobulin structure. First, antigenic region 8 located far from the N-terminal region is in close contact with two remote N-terminal antigenic regions (1 and 4), both involved in hormone formation. This antigenic region is likely to play a role in the correct positioning of hormonogenic tyrosines so as to optimize iodination-coupling reactions. Secondly, the domain involved in the binding of thyroglobulin to its receptor, probed by three mAb, is shared by two distinct mid-molecule antigenic regions, one being the main autoantigenic region of thyroglobulin.
Erregragui
K
K
Immunotech, Marseille, France.
Prato
S
S
Miquelis
R
R
Barrande
C
C
Daniel
C
C
Fert
V
V
D000478:Alkylation; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001665:Binding Sites; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007120:Immunochemistry; D051379:Mice; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D011956:Receptors, Cell Surface / Q000378:metabolism; D013954:Thyroglobulin / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D014357:Trypsin
D000911:Antibodies, Monoclonal; D000939:Epitopes; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; C032198:thyroglobulin receptor; D013954:Thyroglobulin; D014357:Trypsin