HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Almeida, M. R. Articles by Saraiva, M. J. Search for Related Content PubMed Articles by Almeida, M. R. Articles by Saraiva, M. J.

Thyroxine binding to transthyretin (TTR) variants—two variants (TTR Pro 55 and TTR Met 111) with a particularly low binding affinity

Almeida MR, Saraiva MJ. Thyroxine binding to transthyretin (TTR) variants—two variants (TTR Pro 55 and TTR Met 111) with a particularly low binding affinity. Eur J Endocrinol 1996;135:226–30. ISSN 0804–4643

Thyroxine (T₄) binding is a well-characterized function of transthyretin (TTR) and has been used to assess structural alterations of TTR variants. Most TTR variants deposit as amyloid fibrils originating different forms of hereditary amyloidosis. It has been hypothesized that amino acid substitutions in the TTR variants induce structural alterations that may be responsible for the amyloidogenicity of the mutant proteins. To test for structural alterations in TTR, we studied T₄ binding to TTR variants both in whole serum and in isolated form obtained from heterozygotic carriers of amyloidogenic and non-amyloidogenic variants and compared the binding with the corresponding homozygotic recombinant variants. The results obtained indicated a normal T₄ binding affinity for heterozygotic TTR Ala 49, TTR Leu 68, TTR Ala 71 and TTR Arg 102. Concerning TTR Pro 55 and TTR Met 111, we found a consistent decrease in binding affinity. These results were more pronounced for the equivalent recombinant proteins. Recombinant TTR Pro 55 did not show specific binding to T₄ and recombinant TTR Met 111 presented very low binding affinity. Neither TTR Pro 55 nor TTR Met 111 are localized in the T₄ binding channel, thus structural alterations induced by these mutations should be transmitted to the binding channel interfering with T₄ binding. The results now reported, together with ongoing structural data by X-ray analyses on mutants Pro 55 and Met 111 and future binding studies with other ligands, will contribute to the elucidation of the structure and function of TTR, particularly in thyroid hormone metabolism.

Maria João Saraiva, Centro de Estudos de Paramiloidose, Hospital de Santo António, 4050 Porto, Portugal

This article has been cited by other articles:

				A. D. Ferrao-Gonzales, S. O. Souto, J. L. Silva, and D. Foguel The preaggregated state of an amyloidogenic protein: Hydrostatic pressure converts native transthyretin into the amyloidogenic state PNAS, June 6, 2000; 97(12): 6445 - 6450. [Abstract] [Full Text] [PDF]