A 40 kDa inhibitor of protein kinase C purified from bovine brain

AbstractAn inhibitor of protein kinase C has been purified to homogeneity from bovine brain cytosol by a four-step method. It is heat stable, has an apparent molecular mass of 40 kDa and is composed of two polypeptide chains of 19 kDa

towards chameleon detergents for 2-D gel electrophoresis

Caged non-ionic detergents, comprised of polar oligo(ethylene glycol) and non- polar alkyl chains joined by a photocleavable ortho-nitrobenzyl sulfonate linker have been synthesized and characterized. The light-triggered transformation of such chameleon surfactant from a charge-neutral into a charged form offers great potential to improve 2-D gel electrophoretic separation of complex protein mixtures

Expression of a novel versican variant in dorsal root ganglia from spared nerve injury rats

The size and modular structure of versican and its gene suggest the existence of multiple splice variants. We have identified, cloned, and sequenced a previously unknown exon located within the noncoding gene sequence downstream of exon 8. This exon, which we have named exon 8β, specifies two stop-codons. mRNAs of the versican gene with exon 8β are predicted to be constitutively degraded by nonsense-mediated RNA decay. Here, we tested the hypothesis that these transcripts become expressed in a model of neuropathic pain

Location of the Polyamine Binding Site in the Vestibule of the Nicotinic Acetylcholine Receptor Ion Channel

To map the structure of a ligand-gated ion channel, we used the photolabile polyamine-containing toxin MR44 as photoaffinity label. MR44 binds with high affinity to the nicotinic acetylcholine receptor in its closed channel conformation. The binding stoichiometry was two molecules of MR44 per receptor monomer. Upon UV irradiation of the receptor-ligand complex, (125)I-MR44 was incorporated into the receptor alpha-subunit. From proteolytic mapping studies, we conclude that the site of (125)I-MR44 cross-linking is contained in the sequence alpha His-186 to alpha Leu-199, which is part of the extracellular domain of the receptor. This sequence partially overlaps in its C-terminal region with one of the three loops that form the agonist-binding site. The agonist carbachol and the competitive antagonist alpha-bungarotoxin had only minor influence on the photocross-linking of (125)I-MR44. The site where the hydrophobic head group of (125)I-MR44 binds must therefore be located outside the zone that is sterically influenced by agonist bound at the nicotinic acetylcholine receptor. In binding and photocross-linking experiments, the luminal noncompetitive inhibitors ethidium and triphenylmethylphosphonium were found to compete with (125)I-MR44. We conclude that the polyamine moiety of (125)I-MR44 interacts with the high affinity noncompetitive inhibitor site deep in the channel of the nicotinic acetylcholine receptor, while the aromatic ring of this compound binds in the upper part of the ion channel (i.e. in the vestibule) to a hydrophobic region on the alpha-subunit that is located in close proximity to the agonist binding site. The region of the alpha-subunit labeled by (125)I-MR44 should therefore be accessible from the luminal side of the vestibule

Ligand binding to nicotinic acetylcholine receptor investigated by surface plasmon resonance

Ligand binding to the nicotinic acetylcholine receptor is studied by surface plasmon resonance. Biotinylated bungarotoxin, immobilized on a streptavidin-coated gold film, binds nicotinic acetylcholine receptor both in detergent-solubilized and in lipid vesicle-reconstituted form with high specificity. In the latter case, nonspecific binding to the sensor surface is significantly reduced by reconstituting the receptor into poly(ethylene glycol)-lipid-contg. sterically stabilized vesicles. By preincubation of a bulk nicotinic acetylcholine receptor sample with the competing ligands carbamoylcholine and decamethonium bromide, the subsequent specific binding of the receptor to the surface-immobilized bungarotoxin is reduced, depending on the concn. of competing ligand. This competition assay allows the detn. of the dissocn. consts. of the acetylcholine receptor-carbamoylcholine complex. A KD = 3.5 * 10-6 M for the detergent-solubilized receptor and a KD = 1.4 * 10-5 M for the lipid vesicle-reconstituted receptor are obtained. For decamethonium bromide, a KD = 4.5 * 10-5 M is detd. for the detergent-solubilized receptor. This approach is of general importance for investigating ligand-receptor interactions in case of small ligand mols. by mass-sensitive techniques. [on SciFinder (R)

Rôle des cellules gliales lors de la différenciation des cellules ganglionnaires rétiniennes (CGR) de rat

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceGermanyFRD