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G Fillion

Publications and source records attributed to G Fillion.

114 records · Page 7Linked to original sources
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Solubilization and characterization of [3H] 5HT high affinity binding sites (5HT1 and 5HT3).

The solubilization of the serotonergic 5HT1 and 5HT3 sites was performed with digitonin and sodium cholate at 1% (final concentration). Two binding sites for [3H]5HT were observed on rat or horse brain synaptosomal membranes solubilized with these detergents. The corresponding dissociation constants (KD) were 1-3 nM and 13-30 nM respectively. These values were closely similar to those corresponding to 5HT1 and 5HT3 sites located in intact membranes. The solubilized sites specifically bound 5HT. The effect of GTP decreasing the binding to 5HT1 sites was lost on solubilized 5HT1 sites; it was recovered, however, by addition of phospholipids (asolectin 0,2%). The apparent molecular weights of these sites were determined using the gel filtration method (438 and 235 K daltons). The photoactivation of [3H]5HT by U.V. light was used to label 5HT1 and 5HT3 sites irreversively in membranes. The binding of [3H]5HT following U.V. irradiation was not dissociated after dilution; it was saturable and prevented by serotonergic drugs and not by adrenergic or dopaminergic antagonists. Moreover, GTP added prior to the irradiation reduced it markedly thus showing that 5HT1 sites were labelled. Electrophoretic and fluorographic analyses of the labelled material evidenced a 60 K dalton-band specifically labelled with [3H]5HT (5 or 20 nM). These results tend to indicate that the 60 K dalton-proteic band might represent a proteic subunit constituting part of 5HT1 and 5HT3 sites.

Animals↗
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A method for cooperative or noncooperative binding studies using nonlinear regression analysis on a microcomputer.

Ligand-macromolecule interactions are studied by nonlinear regression analysis performed using a microcomputer (SYMAG-Micromachine 3000/Z). The basic phenomenon is described by the Clark equation B = (Formula: see text), where B and F represent bound and free ligand, respectively, Ni the total concentration of binding sites, and Ki their corresponding affinity constant. The programs of calculation have been extended also for Hill and for Adair equations using the Gauss algorithm described by E. E. Beaulieu and J. P. Raynaud [Eur. J. Biochem. 13, 293 (1970)]. A statistical test of F type is introduced to test the quality of the fit and compare the representations of the phenomenon using the different equations.

Animals↗
PubMedDate not supplied

[Fundamental aspects of molecular biology. The multigene family of 5-HT1 receptors].

Genes, constituted by the deoxyribonucleic acid (DNA) contain all the genetic information of a cell. DNA is a double helix consisting of two antiparallel polynucleotide chains where each nucleotide is composed of the association between a base, a sugar and a phosphate group. The chains are associated by hydrogen bonds between the bases. Guanine bonds specifically with cytosine while adenine bonds specifically with thymine. The sequence of DNA is related to the sequence of protein by the genetic code. Each aminoacid is represented by a codon that consists of a nucleotide triplet. Information is expressed by a two-step process. The first step, transcription generates a single-stranded ribonucleic acid called messenger RNA (mRNA) (where a uracil base is present instead of a thymine) which acts as an intermediate molecule. In this step, RNA splicing is one of the maturation processes consisting of joining the exons by removing the introns of the precursor RNA molecule. The second step, translation, converts the nucleotide sequence into the sequence of aminoacids. Since the 1970s, the progress in DNA technology consisting of the development of molecular cloning, DNA library construction and sequencing methods, has made it possible to isolate and analyze specific genes directly from the genome. A sequence of genomic or complementary DNA (cDNA) is cloned by inserting it into a vector (plasmid or phage) that can replicate independently in bacteria. Before cloning, genomic DNA is digested into fragments by restriction enzymes (endonucleases cleaving specific sequences within double-stranded DNA) whereas RNA sequences are copied into cDNA by reverse transcriptase.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗