title: Binding of thyroglobulin to bovine thyroid membranes. Role of specific amino acids in receptor recognition.
abstract: Bovine thyroglobulin was treated with increasing ratios of succinic anhydride, trinitrobenzene sulfonic acid, tetranitromethane, and N-acetylimidazole in an attempt to assess the role of lysine or tyrosine residues in binding to thyroid membrane receptors. Extensive succinylation results in dissociation to 12 S thyroglobulin with retention of a considerable portion of the three-dimensional structure. Only 25% of the lysine residues can be modified by trinitrophenylation without affecting inter-subunit interactions. Succinylation as well as trinitrophenylation increases the affinity of thyroglobulin for the membrane receptor by a factor of 2. The binding of thyroglobulin to the membrane was reduced after nitration of 30% of the tyrosyl residues with tetranitromethane. O-Acetylation of 40-70% of the tyrosyl residues by N-acetylimidazole nearly abolished the ability of thyroglobulin to bind to the membrane. Removal of the O-acetyl group with hydroxylamine restored the binding properties. The results indicate that tyrosyl residues play an important role in thyroglobulin interactions with thyroid membranes.
mesh_terms: D000596:Amino Acids; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D008239:Lysine; D011956:Receptors, Cell Surface / Q000378:metabolism* / Q000494:pharmacology; D013387:Succinic Anhydrides / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013774:Tetranitromethane / Q000494:pharmacology; D013954:Thyroglobulin / Q000378:metabolism*; D013961:Thyroid Gland / Q000378:metabolism*; D014302:Trinitrobenzenesulfonic Acid / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D007093:Imidazoles; D011956:Receptors, Cell Surface; D013387:Succinic Anhydrides; D013439:Sulfhydryl Reagents; C032198:thyroglobulin receptor; D014302:Trinitrobenzenesulfonic Acid; D013954:Thyroglobulin; D013774:Tetranitromethane; D008239:Lysine; C012160:N-acetylimidazole