| Similar hormone-rich peptides from thyroglobulins of five vertebrate classes. | |
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MedLine Citation:
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PMID: 6606572 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Thyroglobulins (Tgs) were purified from five species (rat, chicken, turtle, frog, and goldfish), each representing a different vertebrate class. On reduction with mercaptoethanol, each Tg produced five major iodopeptides, designated A-E, with ranges of estimated molecular mass, in kilodaltons (K), as follows: A, more than 300K; B, 210-280K; C, 30-42K; D, 19-28K; and E, 10-23K. Of these, the two smallest, D and E, had 40-80% of their iodine as iodothyronine, compared with 15-20% for the parent Tgs. They contained 25-63% of Tg's total iodothyronines but only a few percent of its peptide material. Calculations from amino acid analyses and iodine contents showed approximately 1 mol each of D and E/mol 660,000 dalton Tg. In comparisons of amino acid compositions by cluster analysis, iodopeptides D and E resembled each other and their counterparts in other species more than they resembled their parent Tgs. Also, the Tgs from different species were more similar to each other and to iodopeptides D and E than to nonthyroidal proteins randomly selected from the literature. We injected 125I into rats and turtles, and compared its distribution among the iodopeptides to that of 127I. These dual isotope experiments showed that as Tg was iodinated in vivo, iodopeptide B decreased both in molecular size and in its share of Tg's iodine, while the sum of iodopeptides D and E increased, indicating that B may be the precursor of D and E. In vivo iodination of rat Tg with 125I for different periods of time suggested that iodopeptide E and its iodothyronines are derived from a larger portion of the Tg molecule, perhaps iodopeptide B. The amount of 125I in iodopeptide D also increased with time. We conclude that these two discrete hormone-rich peptide fractions of small molecular weight are a consistent feature of Tg's structure throughout the vertebrate classes. Both are probably derived from a larger iodopeptide fraction (iodopeptide B) during the course of Tg maturation and iodination. Their conservation during evolution indicates an important role for them in thyroid hormone biosynthesis. |
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Authors:
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P S Kim; J T Dunn; D L Kaiser |
Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Endocrinology Volume: 114 ISSN: 0013-7227 ISO Abbreviation: Endocrinology Publication Date: 1984 Feb |
Date Detail:
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Created Date: 1984-02-24 Completed Date: 1984-02-24 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0375040 Medline TA: Endocrinology Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 369-74 Citation Subset: AIM; IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Chickens Female Goldfish Iodine Radioisotopes / diagnostic use Molecular Weight Peptides / isolation & purification* Rana pipiens Rats Rats, Inbred Strains Species Specificity Thyroglobulin / isolation & purification* Turtles |
| Grant Support | |
ID/Acronym/Agency:
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5-T35-AM-0719/AM/NIADDK NIH HHS; AM-11043/AM/NIADDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Iodine Radioisotopes; 0/Peptides; 9010-34-8/Thyroglobulin |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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