排序方式: 共有105条查询结果,搜索用时 15 毫秒
41.
Nikolaev VO Gambaryan S Engelhardt S Walter U Lohse MJ 《The Journal of biological chemistry》2005,280(3):1716-1719
Cyclic nucleotide phosphodiesterases (PDEs) are the enzymes that catalyze the hydrolysis of cAMP and cGMP, thereby restricting the activity of these second messengers in cells. A unique ability to shape gradients of cyclic nucleotides and compartmentalize their signaling implies a high potency and a rapid action of PDEs. However, it has not been demonstrated how fast PDEs can hydrolyze cAMP in a living system. Here we perform a real-time monitoring of PDE2 activity in aldosterone-producing adrenal cells using a recently developed genetically encoded, fluorescent cAMP sensor, which reveals enormously rapid kinetics of cAMP degradation. Activation of PDE2 results in a rapid decrease of intracellular cAMP from high micromolar to the sub-micromolar range within a few seconds. Moreover, the kinetics of atrial natriuretic peptide-stimulated PDE2 activity (measured as decline of cAMP) are much faster than the speed of ACTH and isoprenaline-induced cAMP-synthesis (measured as cAMP accumulation) in the cells, revealing high catalytic activity and fast action of PDEs in regulating cAMP signaling in a physiological system. 相似文献
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44.
O. S. Matusovsky V. A. Dyachuk K. V. Kiselev G. G. Matusovskaya N. S. Shelud’ko 《Biophysics》2010,55(5):693-698
The expression of MLCK- and PEVK-domains of twitchin, as well as the unique N-terminal domain of myorod in early development
of the mussel Mytilus trossulus has been studied. The MLCK-domain of twitchin and the unique N-terminal domain of myorod appear at the early stages of development,
whereas the PEVK-domain of twitchin is present only in muscles of adult mussel. The sizes of genes of the N-terminal domain
of myorod, obtained at the blastula stage and from the adult animal are similar, but the proteins have significant differences
in the amino acid sequences. Consequently, myorod and twitchin appear at early stages of larval mussels before the formation
of “adult” muscles capable of catch contraction, and at these stages both proteins are isoforms, which differ from the isoforms
of adult animals. It is possible that the MLCK-domain in the “larval” isoform of twitchin is necessary for regulating the
formation of the contractile apparatus of molluscan smooth muscles, while the PEVK-domain is important for the regulation
of the catch state in muscles of adult animals. 相似文献
45.
Tania Yu. Gromova Ilya V. Demidyuk Viacheslav I. Kozlovskiy Inna P. Kuranova Sergey V. Kostrov 《Biochimie》2009
Protealysin, a protease previously described by us in Serratia proteamaculans, belongs to the group of thermolysin-like proteases (TLPs) that differ from classical TLPs by the precursor structural organization. The propeptide of protealysin precursor has no significant structural similarity to the propeptides of most TLPs. The functions of protealysin-like precursors and mechanisms of their action remain unclear. We studied the pathway of protealysin precursor processing in vitro using standard approaches: modification of the catalytic site and monitoring immobilized precursor maturation. The Glu(113) → Ala substitution inhibited the precursor maturation, which pointed to the autocatalytic processing. The mutant precursor exposure to active protealysin converted it to the mature enzyme, thus, indicating the intermolecular processing. Intermolecular processing of the mutant protein by other proteases such as thermolysin or subtilisin is also possible. The intact protealysin precursor was efficiently autoprocessed in solution but not after immobilization. These data indicate that the processing of protealysin precursor differs from that of classical TLPs. The protealysin propeptide is cleaved by an autocatalytic or heterocatalytic intermolecular mechanism and is most likely not removed intramolecularly. 相似文献
46.
Annika Hofgaard Gareth Rees Hans Tømmervik Olga Tutubalina Elena Golubeva Natalia Lukina Kjell Arild Høgda Stein Rune Karlsen Ludmila Isaeva Viacheslav Kharuk 《应用植被学》2010,13(4):460-472
Question: Is there a need for disturbance mapping integrated in the CircumBoreal Vegetation Mapping Program? Location: Eurasian boreal forest. Disturbance and mapping: The boreal zone is characterized by a multitude of natural and anthropogenic disturbance agents with importance over a wide range of spatial and temporal scales. Disturbance is a prime driver of succession in most of the boreal zone, producing landscape diversity characterized by a large‐scale vegetation mosaic of early to late succession states. When mapping the circumboreal vegetation, spatial extent, time involved from disturbance to recovered condition and likelihood of interacting disturbance types are crucial for how current vegetation is interpreted and subsequently included as map characteristics. In this paper we present examples from the boreal zone where natural and/or anthropogenic disturbance regimes dominate the state and distribution of vegetation, and possibilities for assessing the nature and extent of the disturbed regions using remotely sensed data. Conclusion: Disturbed vegetation occupies large areas in the boreal zone and related vegetation successions should be adequately represented when mapping the zone. In regions where the ‘potential natural vegetation’ is a hypothetical reconstruction from remnants of ‘natural’ vegetation it would be preferable to use the concept of ‘actual real vegetation’ for which remote sensing at coarse, medium and fine resolution is an efficient tool. The Land Cover Classification System (LCCS) may offer sufficient flexibility to incorporate information about the disturbance of circumboreal vegetation. 相似文献
47.
Hein P Rochais F Hoffmann C Dorsch S Nikolaev VO Engelhardt S Berlot CH Lohse MJ Bünemann M 《The Journal of biological chemistry》2006,281(44):33345-33351
To analyze individual steps of G(S)-linked signaling in intact cells, we used fluorescence resonance energy transfer (FRET)-based assays for receptor-G protein interaction, G protein activation, and cAMP effector activation. To do so, we developed a FRET-based sensor to directly monitor G(S) activation in living cells. This was done by coexpressing a Galpha(s) mutant, in which a yellow fluorescent protein was inserted, together with cyan fluorescent protein-tagged Gbetagamma subunits and appropriate receptors in HEK293 cells. Together with assays for receptor activation and receptor-G protein interaction, it is possible to characterize large parts of the G(S) signaling cascade. When A(2A)-adenosine or beta(1)-adrenergic receptors are coexpressed with G(S) in HEK293T cells, the receptor-G(S) interaction was on the same time scale as A(2A) receptor activation with a time constant of <50 ms. G(S) activation was markedly slower and around 450 ms with similar kinetics following activation of A(2A)- or beta(1)-receptors. Taken together, our kinetic measurements demonstrate that the rate of G(S) activation limits initiation of G(S)-coupled receptor signaling. 相似文献
48.
Nelly A. Odintsova Vyacheslav A. Dyachuk Leonid P. Nezlin 《Cell and tissue research》2010,339(3):625-637
Molluscan in vitro technology allows the study of the differentiation of isolated cells undergoing experimental manipulations.
We have used the immunofluorescence technique and laser scanning microscopy to investigate the organization of muscle proteins
(actin, myosin, paramyosin, and twitchin) and the localization of neurotransmitters (serotonin and FMRFamide) in cultured
mussel larval cells. Differentiation into muscle and neuron-like cells occurs during the cultivation of mussel cells from
premyogenic and prenervous larval stages. Muscle proteins are colocalized in contractile cells through all stages of cultivation.
The cultivation of mussel cells on various substrates and the application of integrin receptor blockers suggest that an integrin-dependent
mechanism is involved in cell adhesion and differentiation. Dissociated mussel cells aggregate and become self-organized in
culture. After 20 days of cultivation, they form colonies in which serotonin- and FMRFamide-immunoreactive cells are located
centrally, whereas muscle cells form a contractile network at the periphery. The pattern of thick and thin filaments in cultivated
mussel cells changes according to the scenario of muscle arrangement in vivo: initially, a striated pattern of muscle filaments
forms but is then replaced by a smooth muscle pattern with a diffuse distribution of muscle proteins, typical of muscles of
adult molluscs. Myogenesis in molluscs thus seems to be a highly dynamic and potentially variable process. Such a “flexible”
developmental program can be regarded as a prerequisite for the evolution of the wide variety of striated and smooth muscles
in larval and adult molluscs. 相似文献
49.
Viacheslav V. Trush Sergiy O. Cherenok Vsevolod Yu. Tanchuk Valery P. Kukhar Vitaly I. Kalchenko Andriy I. Vovk 《Bioorganic & medicinal chemistry letters》2013,23(20):5619-5623
Сalix[4]arenes bearing methylenebisphosphonic or hydroxymethylenebisphosphonic acid fragments at the wide rim of the macrocycle were studied as inhibitors of PTP1B. Some of the inhibitors showed IC50 values in the micromolar range and good selectivity in comparison with other protein tyrosine phosphatases such as TC-PTP, PTPβ, LAR, and CD45. Kinetic studies indicated that the calix[4]arene derivatives influence PTP1B activity as slow-binding inhibitors. Based on molecular docking results, the binding modes of the macrocyclic bisphosphonates in the active centre of PTP1B are discussed. 相似文献
50.
Mukherjee M Ge G Zhang N Huang E Nakamura LV Minor M Fofanov V Rao PH Herron A Pati D 《PloS one》2011,6(7):e22167