Assessment of the shape and molecular size of TSH-TSH receptor complexes

Furmaniak, Jadwiga, Davies Jones, E., Buckland, Paul Robert, Howells, Roger David and Rees Smith, Bernard 1986. Assessment of the shape and molecular size of TSH-TSH receptor complexes. Molecular and Cellular Endocrinology 48 (1) , pp. 31-38. 10.1016/0303-7207(86)90163-2

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Abstract

Photoaffinity labelling and analysis under denaturing conditions (SDS-PAGE) have shown that the porcine TSH receptor contains an A subunit (Mr = 47 000) which forms the binding site for TSH and a B subunit (Mr = 25 000) linked to the A subunit by a disulphide bridge. In order to assess the size and shape of the receptor under non-denaturing conditions we have solubilized photoaffinity-labelled porcine TSH receptors using the small micelle-sized detergent sodium deoxycholate and analysed the preparations by sucrose density gradient centrifugation and gel filtration. Under these conditions, the cross-linked TSH-TSH receptor complex showed an s20,w of 6.4 S and a frictional ratio f/f0 of 1.8. These values were consistent with those which might be expected from an elongated protein complex with a molecular weight of about 100 000 (the value obtained by SDS-PAGE). Analysis of another thyroid membrane protein, human thyroid microsomal antigen (Mr = 110 000 by SDS-PAGE) under the same conditions gave an s20,w of 6.0 S and f/f0 = 1.3, suggesting that this protein has a compact structure. The TSH receptor A subunit cross-linked to TSH (Mr = 70000 by SDS-PAGE) gave an s20,w of 4.6 S and f/f0 = 1.8 and these values could be compared with those obtained for the A subunit alone (s20.w =3.6 S; ///q = 1.4; M,, by SDS-PAGE = 47000) and TSH alone (s20,w = 2.6 S; f/f0 = 1.6; Mr = 28000). The data indicate that when TSH (which has an elongated structure) combines with the TSH receptor A subunit (which has a compact structure) the two proteins do not fold into each other extensively but form a structure with an even greater degree of elongation.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	MRC Centre for Neuropsychiatric Genetics and Genomics (CNGG) Medicine
Subjects:	R Medicine > R Medicine (General)
ISSN:	0303-7207
Last Modified:	12 Dec 2022 08:47
URI:	https://orca.cardiff.ac.uk/id/eprint/57614

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