Search results for " Subunit"

HSP60 activity on human bronchial epithelial cells

2017

HSP60 has been implicated in chronic inflammatory disease pathogenesis, including chronic obstructive pulmonary disease (COPD), but the mechanisms by which this chaperonin would act are poorly understood. A number of studies suggest a role for extracellular HSP60, since it can be secreted from cells and bind Toll-like receptors; however, the effects of this stimulation have never been extensively studied. We investigated the effects (pro- or anti-inflammatory) of HSP60 in human bronchial epithelial cells (16-HBE) alone and in comparison with oxidative, inflammatory, or bacterial challenges. 16-HBE cells were cultured for 1–4 h in the absence or presence of HSP60, H2O2, lipopolysaccharide (…

alpha 2-COP is involved in early secretory traffic in Arabidopsis and is required for plant growth

2017

[EN] COP (coat protein) I-coated vesicles mediate intra-Golgi transport and retrograde transport from the Golgi to the endoplasmic reticulum. These vesicles form through the action of the small GTPase ADP-ribosylation factor 1 (ARF1) and the COPI heptameric protein complex (coatomer), which consists of seven subunits (alpha-, beta-, beta' -, gamma-, delta-, epsilon- and xi-COP). In contrast to mammals and yeast, several isoforms for coatomer subunits, with the exception of gamma and delta, have been identified in Arabidopsis. To understand the role of COPI proteins in plant biology, we have identified and characterized a loss-of-function mutant of alpha 2-COP, an Arabidopsis alpha-COP isofo…

More than a pore: How voltage-gated calcium channels act on different levels of neuronal communication regulation.

2021

ABSTRACT Voltage-gated calcium channels (VGCCs) represent key regulators of the calcium influx through the plasma membrane of excitable cells, like neurons. Activated by the depolarization of the membrane, the opening of VGCCs induces very transient and local changes in the intracellular calcium concentration, known as calcium nanodomains, that in turn trigger calcium-dependent signaling cascades and the release of chemical neurotransmitters. Based on their central importance as concierges of excitation-secretion coupling and therefore neuronal communication, VGCCs have been studied in multiple aspects of neuronal function and malfunction. However, studies on molecular interaction partners …

Structural and Functional Characterization of Autophosphorylation in Bacterial Histidine Kinases

2019

Autophosphorylation of histidine kinases (HK) is the first step for signal transduction in bacterial two-component signalling systems. As HKs dimerize, the His residue is phosphorylated in cis or trans depending on whether the ATP molecule used in the reaction is bound to the same or the neighboring subunit, respectively. The cis or trans autophosphorylation results from an alternative directionality in the connection between helices α1 and α2 in the HK DHp domain, in such a way that α2 could be oriented almost 90° counterclockwise or clockwise with respect to α1. Sequence and length variability of this connection appears to lie behind the different directionality and is implicated in partn…

Characterization of crustacyanin-A2 subunit as a component of the organic matrix of gastroliths from the crayfish Cherax quadricarinatus.

2009

AbstractLike the lobsters, some terrestrial crabs and other crayfishes, the Australian red claw crayfish, Cherax quadricarinatus, elaborates in its stomach wall calcium storage structures called gastroliths. For understanding the cyclic elaboration and stabilization of these amorphous calcified structures, we studied the organic matrix (OM) of these paired biomineralizations. After decalcification with acetic acid, we analysed the proteinaceous components of an acetic acid-insoluble fraction by two-dimensional electrophoresis. Nine spots were digested by trpsin and the tryptic peptides were sequenced by nanoLC-nanoESI-MS/MS mass spectrometry. About 100 peptidic sequences were compared to se…

Conversion of the Ca2+-ATPase from Rhodospirillum rubrum into a Mg2+-dependent enzyme by 1,N6-etheno ATP

1980

Nucleoside triphosphate hydrolysis of R.rubrum ATPase complexes can be changed from Ca2+-dependence to Mg2+-dependence by replacing ATP with 1,N6-etheno ATP. Four ATPase complexes which have been prepared by different procedures hydrolyze ATP and 1,N6-etheno ATP at different rates in dependence on the added metal ions. These differences allow an easy distinction of the various enzyme forms.

Structural and Dynamic Properties of the Homodimeric Hemoglobin from Scapharca inaequivalvis Thr-72→Ile Mutant: Molecular Dynamics Simulation, Low Te…

1998

AbstractMolecular dynamics simulations, low temperature visible absorption spectroscopy, and resonance Raman spectroscopy have been performed on a mutant of the Scapharca inaequivalvis homodimeric hemoglobin, where residue threonine 72, at the subunit interface, has been substituted by isoleucine. Molecular dynamics simulation indicates that in the Thr-72→Ile mutant several residues that have been shown to play a role in ligand binding fluctuate around orientations and distances similar to those observed in the x-ray structure of the CO derivative of the native hemoglobin, although the overall structure remains in the T state. Visible absorption spectroscopy data indicate that in the deoxy …

2004

We investigated how the synthesis of cAMP, stimulated by isoproterenol acting through β-adrenoreceptors and Gs, is strongly amplified by simultaneous incubation with baclofen. Baclofen is an agonist of δ-aminobutyric acid type B receptors [GABAB], known to inhibit adenylyl cyclase via Gi. Because these agents have opposite effects on cAMP levels, the unexpected increase in cAMP synthesis when they are applied simultaneously has been intensively investigated. From previous reports, it appears that cyclase type II contributes most significantly to this phenomenon. We found that simultaneous application of isoproterenol and baclofen specifically influences the association/dissociation of molec…

Lack of correlation between expression of HIF-1alpha protein and oxygenation status in identical tissue areas of squamous cell carcinomas of the uter…

2004

Abstract Hypoxia inducible factor-1α (HIF-1α) has been proposed as a candidate endogenous marker of tumor hypoxia and as a molecular mediator of hypoxia-driven malignant progression and acquired treatment resistance. In this study, HIF-1α expression in 68 biopsies of oxygenation measurement tracks from squamous cell carcinomas of the uterine cervix of 38 patients was assessed. Expression of HIF-1α was commonly found to increase as a function of distance from microvessels, at the center of tumor cell aggregations, and in the vicinity of necrotic areas. However, there was no correlation of HIF-1α expression with median oxygen tension (oxygen partial pressure; pO2) and hypoxic fractions (hypox…

Effect of IL-13 receptor α2 levels on the biological activity of IL-13 variant R110Q

2007

Background IL-13 is a key cytokine associated with the asthmatic phenotype. IL-13 signals via its cognate receptor, a complex of IL-13 receptor (IL-13R) α 1 chain with IL-4 receptor α; however, a second protein, IL-13Rα2, also binds IL-13. Recently a polymorphic variant of IL-13 (R110Q) has been shown to be associated with atopy. Objective To investigate the binding properties of this IL-13 variant to its cognate receptors. Methods We used surface plasmon resonance to measure the binding kinetics of R110Q to its receptors. Primary human fibroblasts were grown from endobronchial biopsies obtained from volunteers. Receptor levels were measured by fluorescence-activated cell sorting. Results T…