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M Parmentier

Publications and source records attributed to M Parmentier.

At least 163 records · Page 9Linked to original sources
PubMed1990

Molecular cloning of a dog thyrotropin (TSH) receptor variant.

A clone coding for a variant form of thyrotropin receptor was isolated from a dog thyroid cDNA library. It was characterized by a 75 bp deletion in the coding region, additionally to minor modifications in the 3' untranslated region. The corresponding 25 amino acids deletion is located in the long NH2 terminal extracellular domain which is characteristic of the glycoprotein hormone receptors. This region of the protein is composed of imperfect repeats and the deletion corresponds exactly to one of the repeat units. This suggests that the repeats correspond to individual exons in the thyrotropin receptor chromosomal gene. It is not known whether the deletion of the repeat and the concomitant suppression of one of the N-glycosylation sites of the molecule do alter the receptor function.

Amino Acid Sequence↗
PubMed1990

Tissue-specific expression and methylation of a thyroglobulin-chloramphenicol acetyltransferase fusion gene in transgenic mice.

Fusion genes containing 1600 or 2000 base pairs of the bovine thyroglobulin gene 5' flanking region and the chloramphenicol acetyltransferase (CAT) coding sequence were constructed and used to generate transgenic mice. Altogether, 24 independent transgenic lines were obtained, and the expression of the transgene was assayed by measuring the CAT activity in different tissues. Depending on the transgenic lines, the fusion gene was either silent in all tissues or specifically expressed in the thyroid. The level of expression was found to be highly variable from one line to another and to be regulated by thyrotropin in a manner similar to the natural thyroglobulin gene. The methylation status of the integrated DNA was tested by digestion of DNA extracted from thyroid and other tissues with the isochizomers Msp I and Hpa II. It was found that one of the Hpa II sites was demethylated specifically in the thyroid.

Animals↗
PubMed1990

Calbindin D28k is essentially located in the colonic part of the toad intestine.

The distribution of calbindin D28k in the digestive system and the urinary bladder of the toad was investigated using immunohistochemistry and Western blotting. By analogy with mammals and birds, the protein was expected to be located preferentially in the duodenal part of the intestine. Interestingly, absorptive cells of the duodenum were totally devoid of calbindin D28k while the colon contained high amounts of the calcium-binding protein. This reversed polarity of calbindin D28k content in the toad intestine should obviously correspond to a different scheme of calcium absorption regulation between amphibians and higher vertebrates. Calbindin D28k containing neuroendocrine-like cells were found scattered in the proximal parts of the gut with a similar distribution to what has been described in rat and chick intestine. The oesophagus, the stomach, and the intrinsic nervous system of the intestine were negative. No significant amounts of the proteins were found in the urinary bladder, which is known to be a site of Ca2+ active transport.

Animals↗
PubMed1989

Cloning, sequencing and expression of the human thyrotropin (TSH) receptor: evidence for binding of autoantibodies.

A human thyroid cDNA library was screened by hybridization with a dog thyrotropin receptor (TSHr) cDNA. Sequencing of the resulting clones identified a 2292 residue open reading frame encoding a 744 amino acid mature polypeptide presenting 90.3% similarity with the dog TSHr. Two major transcripts (4.6 and 4.4 kilobases) were identified in the human thyroid which suggests that alternative splicing could generate multiple forms of human TSHr. Transfection of the coding sequence in COS-7 cells conferred to a membrane preparation of these cells the ability to bind specifically TSH. TSH binding was completely displaced by immunoglobulin preparations from patients with idiopathic myxoedema.

Amino Acid Sequence↗
PubMed1989

Molecular cloning of the thyrotropin receptor.

The pituitary hormone thyrotropin, or thyroid-stimulating hormone (TSH), is the main physiological agent that regulates the thyroid gland. The thyrotropin receptor (TSHR) was cloned by selective amplification with the polymerase chain reaction of DNA segments presenting sequence similarity with genes for G protein-coupled receptors. Out of 11 new putative receptor clones obtained from genomic DNA, one had sequence characteristics different from all the others. Although this clone did not hybridize to thyroid transcripts, screening of a dog thyroid complementary DNA (cDNA) library at moderate stringency identified a cDNA encoding a 4.9-kilobase thyroid-specific transcript. The polypeptide encoded by this thyroid-specific transcript consisted of a 398-amino acid residue amino-terminal segment, constituting a putative extracellular domain, connected to a 346-residue carboxyl-terminal domain that contained seven putative transmembrane segments. Expression of the cDNA conferred TSH responsiveness to Xenopus oocytes and Y1 cells and a TSH binding phenotype to COS cells. The TSHR and the receptor for luteinizing hormone-choriogonadotropin constitute a subfamily of G protein-coupled receptors with distinct sequence characteristics.

Amino Acid Sequence↗
PubMed1989

Selective amplification and cloning of four new members of the G protein-coupled receptor family.

An approach based on the polymerase chain reaction has been devised to clone new members of the family of genes encoding guanosine triphosphate-binding protein (G protein)-coupled receptors. Degenerate primers corresponding to consensus sequences of the third and sixth transmembrane segments of available receptors were used to selectively amplify and clone members of this gene family from thyroid complementary DNA. Clones encoding three known receptors and four new putative receptors were obtained. Sequence comparisons established that the new genes belong to the G protein-coupled receptor family. Close structural similarity was observed between one of the putative receptors and the 5HT1a receptor. Two other molecules displayed common sequence characteristics, suggesting that they are members of a new subfamily of receptors with a very short nonglycosylated (extracellular) amino-terminal extension.

Amino Acid Sequence↗
PubMed1989

Calbindin-D28 in mammalian brain, retina, and endocrine pancreas: immunohistochemical comparison with calretinin.

Calbindin 28K and calretinin are very similar calcium binding proteins which are both present in the central nervous system (CNS). They respectively bind 4 and 5 Ca++ ions. We have compared by immunohistochemistry and in situ hybridization their localisation in the brain and the retina. The two proteins are generally expressed in different neurons with a few neurons containing both calcium binding proteins. Calbindin 28K is also present in the endocrine system. We have examined the cellular distribution of calbindin in the pancreatic endocrine cells of chick, rat and human and found variable distribution among the different endocrine cell types. We also describe the presence of calbindin in RINm5F cells, an insulin-producing tumor cell line derived from a radiation-induced rat insulinoma.

Animals↗
PubMed1989

The human calbindin 27-kDa gene: structural organization of the 5' and 3' regions, chromosomal assignment, and restriction fragment length polymorphism.

The 5' and 3' regions of the human gene coding for calbindin 27 kDa were cloned and sequenced. Structural features of the 5' region included the presence of an Alu repeat and two elements regularly associated with eukaryotic promoters: an alternating purine-pyrimidine element and a homopurine-homopyrimidine box. The 3' region contained a second Alu family member and a degenerate 1.4-kb L1 repeat. A comparison with the chicken promoter was made in order to define regions conserved in evolution and potentially important in gene expression regulation. The greater similarity is located around the TATA box, but strongly conserved elements were not found. The gene was assigned to chromosome 8 by using human-rodent hybrid cell lines. Two restriction fragment length polymorphisms (HindIII and SacI) were detected with a cDNA probe recognizing the 3' end of the gene.

Amino Acid Sequence↗
PubMed1989

The human genes for calbindin 27 and 29 kDa proteins are located on chromosomes 8 and 16, respectively.

Genomic clones coding for the brain calcium-binding protein, calbindin 29 kDa, were isolated from a human library. A fragment containing exon 2 was used as a probe to investigate the presence of the gene in human x rodent somatic cell hybrids. The gene was unambiguously assigned to chromosome 16. The closely-related calbindin 27 kDa gene was previously assigned to chromosome 8. These two genes, deriving from a common ancestor, thus appear to have been separated during vertebrate evolution.

Animals↗