Interaction of autoantibodies to thyrotropin receptor with a hydrophilic subunit of the thyrotropin receptor.
Reduction of human thyroid membranes with dithiothreitol caused the release of a water-soluble glycoprotein which neutralized the thyrotropin (TSH) receptor-binding and thyroid-stimulating activities of Graves' serum. Analysis of the protein by gel filtration and sucrose density gradient centrifugation allowed estimates of 3.45 nm for the Stokes' radius, 3.6 S for the s20,w and 47 000 +/- 5000 (mean +/- S.D.; n = 4) for the Mr. The material released by dithiothreitol treatment could be crosslinked to 125I-labelled TSH coupled to N-hydroxysuccinimidyl 4-azidobenzoate (125I-HSAB-TSH), suggesting that it contained a component of the TSH receptor. Furthermore, analysis of the crosslinked material by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis indicated that it contained the TSH receptor A subunit (Mr 50 000). Several factors suggested therefore that the glycoprotein released by dithiothreitol treatment of human thyroid membranes was the TSH receptor A subunit. In particular, (a) both preparations were hydrophilic and were released from membranes by reduction, (b) they had similar Mr values and (c) both preparations crosslinked to 125I-HSAB-TSH. Material similar to the TSH receptor A subunit was released from thyroid membranes by treatment with papain, probably as a result of cleavage of the receptor A subunit at a site close to the interchain disulphide bridge. A similar mechanism, involving thyroid proteinases, was probably involved in release of material with similar properties to the TSH receptor A subunit during freezing and thawing of human thyroid homogenates.
Davies Jones
E
E
Hashim
F A
FA
Kajita
Y
Y
Creagh
F M
FM
Buckland
P R
PR
Petersen
V B
VB
Howells
R D
RD
Rees Smith
B
B
D001323:Autoantibodies / Q000276:immunology*; D001386:Azides; D002462:Cell Membrane / Q000187:drug effects; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D004229:Dithiothreitol / Q000494:pharmacology; D006111:Graves Disease / Q000097:blood; D006801:Humans; D010206:Papain / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000276:immunology*; D011989:Receptors, Thyrotropin; D013961:Thyroid Gland / Q000187:drug effects
D001323:Autoantibodies; D001386:Azides; D011956:Receptors, Cell Surface; D011989:Receptors, Thyrotropin; C029534:hydroxysuccinimidyl-4-azidobenzoate; D010206:Papain; D004229:Dithiothreitol