Neutral trehalase 1 (Nth1) from Saccharomyces cerevisiae
catalyzes disaccharide trehalose hydrolysis and helps yeast to
survive adverse conditions, such as heat shock, starvation or
oxidative stress. 14-3-3 proteins, master regulators of hundreds
of partner proteins, participate in many key cellular processes.
Nth1 is activated by phosphorylation followed by 14-3-3 protein
(Bmh) binding. The activation mechanism is also potentiated by
Ca2+ binding within the EF-hand-like motif. This review
summarizes the current knowledge about trehalases and the
molecular and structural basis of Nth1 activation. The crystal
structure of fully active Nth1 bound to 14-3-3 protein provided
the first high-resolution view of a trehalase from a eukaryotic
organism and showed 14-3-3 proteins as structural modulators
and allosteric effectors of multi-domain binding partners.
Ivermectin acts as a positive allosteric regulator of several ligand gated channels including the glutamate-gated chloride channel (GluCl), γ-aminobutyric acid type-A receptor, glycine receptor, neuronal α 7-nicotinic receptor and purinergic P2X4 receptor. In most of the ivermect in-sensitive channe ls, the effects of ivermectin include the potentiation of agonist-induced currents at low concentrations and channel opening at higher concentrations. Based on mutagenesis, electrophysiological recordings and functional an alysis of chimeras between ivermectin-sensitive and ivermectin-insensitive receptors, it has been concluded that ivermectin acts by insertion between transmembrane helices. The three-dimensional structure of C. elegans GluCl complexed with ivermectin has revealed the details of the ivermectin-binding site, however, no generic motif of amino acids could accurately predict ivermectin binding site for other ligand gated channels. Here, we will review what is currently known about ivermectin binding and modulation of Cys-loop receptor family of ligand-gated ion channels and what are the critical structur al determinants underlying potentiation of the P2X4 receptor channel., H. Zemkova ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Allostery is an essential property of many physiological mechanisms. Cooperativity together with allostery is observed in the behavior of multisubunit receptors. Here we summarize and compare several approaches to the description and analysis of allosteric phenomena with emphasis on the receptors connected to ionic channels as a model. Several simplified methods are discussed in comparison with the microscopic kinetic scheme, affinity-efficacy separation and a thermodynamic approach.
The aim of the experiment was to investigate the mechanism of harmful alloxan action in vivo. 75 mg/kg b.w. of this diabetogenic agent were administered to fasting rats. Two minutes later the animals were decapitated. It was observed that alloxan caused a distinct rise in blood insulin and glucose levels with a concomitant drop of free fatty acids. The amount of sulfhydryl groups in the liver of alloxan-treated rats was decreased and glutathione peroxidase activity was substantially higher. These results indicate that some changes observed in alloxan-induced diabetes can not only be the consequence of B cells damage by alloxan but may also be the result of its direct influence on other tissues. It was also observed that glucose given 20 min before alloxan injection only partially protected against the deleterious effects of alloxan.
Allozyme polymorphism was investigated in adult males of the stenotopic peat bog (tyrphobiontic) noctuid moth, Coenophila subrosea Stephens, from three isolated peat bog localities in Austria (Styria) and Czech Republic (South and North Bohemia). Of the eighteen enzyme loci examined, twelve were polymorphic and six monomorphic. Significant deviations of genotype frequencies from Hardy-Weinberg equilibrium were observed at about one third of polymorphic loci within the populations. The average heterozygosities for the populations from three geographically distinct localities ranged from 0.192 to 0.245, and 61% of the loci were polymorphic. The FST mean value of 0.0675 was higher than that found in most other Lepidoptera. The genetic distances based on allozyme heterozygosity ranged from 0.019 to 0.051, with the population from South Bohemia being the most distant. The genetic distances and FST values do not reflect the geographic distances between the populations. Morphometric analysis revealed a difference between the Austrian Purgschachen Moor and Bohemian populations. These isolated relict peat bogs are habitat islands inhabited by unique "geographical races" of tyrphobiontic taxa., Jan Šula, Karel Spitzer, 4 obrázky, 5 tab., and Lit.
Alma mater česká Carolo-Ferdinandea - Alma mater Jagellonica. Vzájemné inspirace a kontakty mezi českou Karlo-Ferdinandovou univerzitou v Praze a Jegellonskou univerzitou v Krakově v letech 1882-1918.
In this paper we establish some conditions for an almost $\pi $-domain to be a $\pi $-domain. Next $\pi $-lattices satisfying the union condition on primes are characterized. Using these results, some new characterizations are given for $\pi $-rings.
Generalizing the notion of the almost free group we introduce almost Butler groups. An almost $B_2$-group $G$ of singular cardinality is a $B_2$-group. Since almost $B_2$-groups have preseparative chains, the same result in regular cardinality holds under the additional hypothesis that $G$ is a $B_1$-group. Some other results characterizing $B_2$-groups within the classes of almost $B_1$-groups and almost $B_2$-groups are obtained. A theorem of stating that a group $G$ of weakly compact cardinality $\lambda $ having a $\lambda $-filtration consisting of pure $B_2$-subgroup is a $B_2$-group appears as a corollary.
We introduce a new class of functions called almost ˜gα-closed and use the functions to improve several preservation theorems of normality and regularity and also their generalizations. The main result of the paper is that normality and weak normality are preserved under almost ˜gα-closed continuous surjections.