Characterization of a hormonogenic domain from human thyroglobulin

Marriq, Claudine; Lejeune, Pierre-Jean; Venot, Nicole; Rolland, Marc; Lissitzky, Serge

doi:10.1016/0014-5793(86)81509-5

Cited by 17 publications

(18 citation statements)

References 16 publications

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“…We had the opportunity to test the properties of several purified Tg peptides disposed at various places along the molecule: the N-terminal domain of Tg (Marriq et al 1986), two type 1 repeats (a kind gift from Dr R Miquelis), the N3 peptide (a kind gift from Dr R Miquelis), which binds to the recycling Tg receptor (Mezghrani et al 1997) and an immunoreactive Tg peptide P40 (of about 40 kDa) (Duthoit et al 2000) (a kind gift from Dr J Ruf ) produced during the hTg oxidative process, located at the C-terminal end of the molecule and including P1. All these peptides but one possess only very limited binding capabilities (results not shown).…”

Section: Discussionmentioning

confidence: 99%

“…CNBr peptides from iodine-poor hTg were prepared and fractionated as described by Marriq et al (1986). In brief, hTg was treated with CNBr and the resulting CNBr peptides were filtered on a Sephadex G-200 column in 1 M propionic acid.…”

Section: Preparation Of Cyanogen Bromide (Cnbr) Peptidesmentioning

confidence: 99%

“…hTg peptides obtained by applying CNBr treatment to hypoiodinated hTg were fractionated on a Sephadex G-200 column as described by Marriq et al (1986). Five fractions labeled I-V were collected.…”

Section: Identification Of Peptides From Htg That Strongly Bind Cell mentioning

confidence: 99%

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Identification of thyroglobulin domain(s) involved in cell-surface binding and endocytosis

Siffroi-Fernandez

Delom²,

Nlend³

et al. 2001

Journal of Endocrinology

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Thyroglobulin (Tg) binds to cell surfaces through various binding sites of high, moderate and low affinity. We have previously shown that binding with low to moderate affinity is pH dependent, selective, but not tissue specific. To identify the regions of Tg involved in this cell surface binding, we studied the binding of 125 I-labeled cyanogen bromide peptides from human Tg to cell surfaces of thyroid cells (inside-out follicles) and of CHO cells. Electrophoretic analysis of cell homogenates after binding of native or of reduced and alkylated 125

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Section: Discussionmentioning

confidence: 99%

Section: Preparation Of Cyanogen Bromide (Cnbr) Peptidesmentioning

confidence: 99%

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Identification of thyroglobulin domain(s) involved in cell-surface binding and endocytosis

Siffroi-Fernandez

Delom²,

Nlend³

et al. 2001

Journal of Endocrinology

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“…Thyroid hormone formation within truncated NH 2 -terminal Tg fragments, derived from the abortive translation of normal-sized mRNAs, was probably responsible for the correction of hypothyroidism, by iodide supplementation, in a strain of Dutch goats with congenital goiter (39 -41), and for euthyroidism in Afrikander cattle (42)(43)(44). Efficient T 4 formation was demonstrated in isolated fragment 1-171 of human Tg (22,34). Thyroid hormones were also formed upon in vitro iodination of a fragment comprising the 224 COOH-terminal amino acids of rat Tg (45).…”

Section: Efficiency Of Tyr-1375 As a T 4 -And T 3 -Forming Site-the Dmentioning

confidence: 99%

Identification of Hormonogenic Tyrosines in Fragment 1218-1591 of Bovine Thyroglobulin by Mass Spectrometry

Gentile

Ferranti²,

Mamone³

et al. 1997

Journal of Biological Chemistry

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A fragment of bovine thyroglobulin encompassing residues 1218 -1591 was prepared by limited proteolysis with thermolysin and continuous-elution polyacrylamide gel electrophoresis in SDS. The reduced and carboxymethylated peptide was digested with endoproteinase Asp-N and fractionated by reverse-phase high performance liquid chromatography. The fractions were analyzed by electrospray and fast atom bombardment mass spectrometry in combination with Edman degradation. The post-translational modifications of all seven tyrosyl residues of the fragment were characterized at an unprecedented level of definition. The analysis revealed the formation of: 1) monoiodotyrosine from tyrosine 1234; 2) monoiodotyrosine, diiodotyrosine, triiodothyronine (T 3 ), and tetraiodothyronine (thyroxine, T 4 ) from tyrosine 1291; and 3) monoiodotyrosine, diiodotyrosine, and dehydroalanine from tyrosine 1375. Iodothyronine formation from tyrosine 1291 accounted for 10% of total T 4 of thyroglobulin (0.30 mol of T 4 /mol of 660-kDa thyroglobulin), and 8% of total T 3 (0.08 mol of T 3 /mol of thyroglobulin). This is the first documentation of the hormonogenic nature of tyrosine 1291 of bovine thyroglobulin, as thyroxine formation at a corresponding site was so far reported only in rabbit, guinea pig, and turtle thyroglobulin. This is also the first direct identification of tyrosine 1375 of bovine thyroglobulin as a donor residue. It is suggested that tyrosyl residues 1291 and 1375 may support together the function of an independent hormonogenic domain in the mid-portion of the polypeptide chain of thyroglobulin.Thyroglobulin (Tg), 1 a homodimeric glycoprotein with a molecular mass of 660 kDa, is the site of the biosynthesis of 3,5,3Ј-triiodothyronine (T 3 ) and 3,5,3Ј,5Ј-tetraiodothyronine (thyroxine, T 4 ) (reviewed in Ref. 1). T 3 and T 4 are synthesized via the iodination and coupling of a small subset of tyrosyl residues within the polypeptide chains of Tg. The coupling reaction takes place by the transfer of an iodophenyl group from a donor 3-monoiodotyrosine or 3,5-diiodotyrosine to an acceptor 3,5-diiodotyrosine. This causes the formation of T 3 or T 4 , respectively, at the acceptor site and dehydroalanine at the donor site (2, 3). Both reactions are catalyzed by thyroid peroxidase. Different tyrosyl residues have different reactivities toward iodine, so that iodination proceeds in a sequential order, which is controlled by the native structure of Tg (4, 5). Early iodinated tyrosyl residues are preferentially involved in iodothyronine synthesis (6); the coupling of iodotyrosines, in turn, has stringent steric requirements (7). In fact, out of 72 tyrosyl residues per bovine Tg monomer, only 15 are iodinated and a maximum of 6 -8 of them undergo coupling to form T 3 and T 4 (8, 9). So far, four major hormonogenic tyrosines have been identified, by the isolation and sequencing of hormone-rich peptides from Tgs of various animal species and comparison of their sequences with the cDNA-deduced sequences of bovine (10) and human Tg (11). Ty...

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“…The NTD issued from this Tg was separated by chromatography on a Sephadex G-200 column (Pharmacia Biotech, Uppsala, Sweden) in 1 M propionic acid [7].…”

Section: Preparation Of the Ntd Of Human Tgmentioning

confidence: 99%

Dityrosine bridge formation and thyroid hormone synthesis are tightly linked and are both dependent on N‐glycans

et al. 1996

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Formation of dityrosine bridges is a ubiquitous process mainly attributed to oxidative stress leading to protein degradation and cellular damages. Here we show that dityrosine formation is involved in a physiological process, thyroid hormone synthesis, and is strictly dependent on structural characteristics, namely N-glycans, presented by the protein acting as the prothyroid hormone. We used two isoforms of the N-terminal thyroid hormone forming domain (NTD) of human thyroglobulin: one without N-glyean (19 kDa isoform) and the other with high mannose type structures (25 kDa isoform). Both isoforms were able to form iodotyrosines after in vitro iodination. However, iodotyrosine coupling to form thyroxine did not occur with the unglycosylated 19 kDa NTD. In contrast, the 25 kDa isoform formed thyroxine. Strikingly, thyroxine synthesis was accompanied by dimerization of the 25 kDa isoform and formation of a dityrosine bridge; none of this was observed with the 19 kDa isoform. Taken as a whole, our results indicate that dimerization through dityrosine bridging accompanies and could have a role in thyroid hormone synthesis.Key words: Thyroid; Hormone synthesis; Glycosylation; Dityrosine ecular heterogeneity. This precludes detailed analysis of the various domains in terms of structure-activity relationship. To circumvent this problem, we focused on the N-terminal domain (NTD) of human Tg, which contains the preferential site of hormone synthesis located at Tyr 5 [4]. This peptide, obtained after CNBr treatment of a poorly iodinated Tg, is able to form hormone (T4) by in vitro iodination and iodotyrosine coupling. It has an apparent molecular mass ranging from 19 to 25 kDa according to the number of oligosaccharide side chains linked at Asn 57 and Asn 9x [5]. The large variability of the N-glycan structures borne by the NTD offered an interesting opportunity to determine the role of N-glycans in thyroid hormone synthesis and their possible association with the dimerization process through formation of dityrosine bridges. We selected two types of NTD: the first was unglycosylated and the second was rich in high mannose structures. We observed that dityrosine bridge formation and thyroid hormone synthesis are both dependent on the N-glycan structures and both the results of the same oxidative process under the action of TPO and the H202 generating system. Materials and mcthods

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Characterization of a hormonogenic domain from human thyroglobulin

Cited by 17 publications

References 16 publications

Identification of thyroglobulin domain(s) involved in cell-surface binding and endocytosis

Identification of thyroglobulin domain(s) involved in cell-surface binding and endocytosis

Identification of Hormonogenic Tyrosines in Fragment 1218-1591 of Bovine Thyroglobulin by Mass Spectrometry

Dityrosine bridge formation and thyroid hormone synthesis are tightly linked and are both dependent on N‐glycans

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