Search results for "binding site"
showing 10 items of 856 documents
Assembly of functional α6β3γ2δ GABAA receptors in vitro
2000
Transgenic mice deficient in the alpha6 subunit of the GABA(A) receptor show reduced levels of the delta subunit protein and an altered GABA(A) receptor pharmacology, suggesting selective assembly mechanisms. Delta reduced the binding of [3H]Ro15-4513 or t-butylbicyclophosphoro[35S]thionate and, to a lesser extent, [3H]muscimol to recombinant alpha1beta1gamma2(delta), alpha4beta1gamma2(delta) and alpha6beta1gamma2(delta) receptors, paralleled by diminished GABA-evoked maximal currents in electrophysiological recordings for the latter one. The delta subunit gave rise to a lower EC50 for GABA and a slowed desensitization indicating its assembly in alpha6beta2delta, alpha6beta1gamma2delta and …
Structural features of the human bradykinin B2 receptor probed by agonists, antagonists, and anti-idiotypic antibodies
1993
The human bradykinin B2 receptor belongs to the family of G-protein-coupled receptors. To characterize the receptor protein, we have solubilized the membranes of cultured human foreskin fibroblasts bearing the B2 receptor. Affinity cross-linking of the solubilized receptor with the labeled agonist, 125I-Tyr0-bradykinin, or the labeled antagonist, 125I-(4-hydroxy-phenyl-propionyl)-HOE140, revealed major bands of apparent molecular mass of 69 kDa in SDS-polyacrylamide gel electrophoresis under reducing conditions, and of 59 kDa under non-reducing conditions. A 1000-fold molar excess of each of the unlabeled ligands quenched the specific labeling suggesting that the agonist and the antagonist …
Phage-borne factors and host LexA regulate the lytic switch in phage GIL01.
2011
ABSTRACT The Bacillus thuringiensis temperate phage GIL01 does not integrate into the host chromosome but exists stably as an independent linear replicon within the cell. Similar to that of the lambdoid prophages, the lytic cycle of GIL01 is induced as part of the cellular SOS response to DNA damage. However, no CI-like maintenance repressor has been detected in the phage genome, suggesting that GIL01 uses a novel mechanism to maintain lysogeny. To gain insights into the GIL01 regulatory circuit, we isolated and characterized a set of 17 clear plaque ( cp ) mutants that are unable to lysogenize. Two phage-encoded proteins, gp1 and gp7, are required for stable lysogen formation. Analysis of …
Homologies Between Different Forms of 2-5A Synthetases
1994
(2′-5′) Oligoadenylate synthetases (2-5A synthetases; EC 2.7.7.19) are present in mammalian cells and tissues and synthesize from ATP a series of oligomers termed 2-5A [general formula: ppp(A2′p)nA; with 1 ≤ n < 18 and usually 1 ≤ n < 6] (Hovanessian 1991). For full enzymic activity of the 2-5A synthetases, binding of double-stranded RNA is required (Sen 1982). Three principal 2-5A synthetase isoenzymes have been described with Mr’s of 40–46, 69, and 100 kDa (Chebath et al. 1987; Hovanessian et al. 1987, 1988). In the following they are classified as 2-5A synthetase I [Mr 40–46 000], II [Mr 69 000] and III [Mr 100 000]. All three isoforms are induced in cells by interferon (Cohen et al. 198…
Genomic Structure and in Vivo Expression of the Human Organic Anion Transporter 1 (hOAT1) Gene
2000
The human organic anion transporter 1 (hOAT1) plays a key role in the secretion of an array of potentially toxic organic anions including many clinically important drugs. Here we report on the genomic cloning of hOAT1. A human genomic library was used for screening of a PAC (P1 artificial chromosome) clone applying PCR techniques. Sequencing of several restriction subclones and of a PCR-generated clone revealed that the hOAT1 gene spans 8.2 kb and is composed of 10 exons divided by 9 introns. RT-PCR studies in a human kidney specimen led to the detection of two new splice variants, hOAT1-3 and hOAT1-4, showing a 132-bp in-frame deletion. Using fluorescence in situ hybridization (FISH) we ma…
Elucidation of the regulation of an adult cuticle gene Acp65A by the transcription factor Broad.
2009
Broad (BR), an ecdysone-inducible transcription factor, is a major determinant of the pupal stage. The misexpression of BR-Z1 isoform (BR-Z1) during adult development of Drosophila melanogaster prevents the expression of the adult cuticle protein 65A gene (Acp65A). We found that the proximal 237 bp of the 5' flanking region of Acp65A were sufficient to mediate this suppression. A targeted point mutation of a putative BR-Z1 response element (BRE) within this region showed that it was not involved. Drosophila hormone receptor-like 38 (DHR38) is required for Acp65A expression. We found that BR-Z1 repressed DHR38 expression and that BR's inhibition of Acp65A expression was rescued by exogenous …
The diversity of GABAA receptors. Pharmacological and electrophysiological properties of GABAA channel subtypes.
1998
The amino acid gamma-aminobutyric-acid (GABA) prevails in the CNS as an inhibitory neurotransmitter that mediates most of its effects through fast GABA-gated Cl(-)-channels (GABAAR). Molecular biology uncovered the complex subunit architecture of this receptor channel, in which a pentameric assembly derived from five of at least 17 mammalian subunits, grouped in the six classes alpha, beta, gamma, delta, sigma and epsilon, permits a vast number of putative receptor isoforms. The subunit composition of a particular receptor determines the specific effects of allosterical modulators of the GABAARs like benzodiazepines (BZs), barbiturates, steroids, some convulsants, polyvalent cations, and et…
β1-Integrin Cytoplasmic Subdomains Involved in Dominant Negative Function
1998
The beta1-integrin cytoplasmic domain consists of a membrane proximal subdomain common to the four known isoforms ("common" region) and a distal subdomain specific for each isoform ("variable" region). To investigate in detail the role of these subdomains in integrin-dependent cellular functions, we used beta1A and beta1B isoforms as well as four mutants lacking the entire cytoplasmic domain (beta1TR), the variable region (beta1COM), or the common region (beta1 deltaCOM-B and beta1 deltaCOM-A). By expressing these constructs in Chinese hamster ovary and beta1 integrin-deficient GD25 cells (Wennerberg et al., J Cell Biol 132, 227-238, 1996), we show that beta1B, beta1COM, beta1 deltaCOM-B, a…
Claudin-18 gene structure, regulation, and expression is evolutionary conserved in mammals
2011
Claudin-18 isoform 2 (CLDN18.2) is one of the few members of the human claudin family of tight junction molecules with strict restriction to one cell lineage. The objective of the current study was to compare molecular structure and tissue distribution of this gastrocyte specific molecule in mammals. We show here that the CLDN18.2 protein sequence is highly conserved, in particular with regard to functionally relevant domains in mouse, rat, rabbit, dog, monkey and human and also in lizards. Moreover, promoter regions of orthologs are highly homologous, including the binding site of the transcription factor cyclic AMP-responsive element binding protein (CREB), which is known to regulate acti…
Hsp70 is required for optimal cell proliferation in mouse A6 mesoangioblast stem cells.
2009
Mouse Hsp70 (70 kDa heat shock protein) is preferentially induced by heat or stress stimuli. We previously found that Hsp70 is constitutively expressed in A6 mouse mesoangioblast stem cells, but its possible role in these cells and the control of its basal transcription remained unexplored. Here we report that in the absence of stress, Ku factor is able to bind the HSE (heat shock element) consensus sequence in vitro, and in vivo it is bound to the proximal hsp70 promoter. In addition, we show that constitutive hsp70 transcription depends on the co-operative interaction of different factors such as Sp1 (specificity protein 1) and GAGA-binding protein with Ku factor, which binds the HSE cons…