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1
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Regulation of nuclear phospholipase C activity.

100%
Manzoli L., Billi A. M., Martelli A. M., Cocco L.
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vol. 51
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issue 2
391-395
EN
A body of evidence, linking inositide-specific phospholipase C (PI-PLC) to the nucleus, is quite extensive. The main isoform in the nucleus is PI-PLCβ1, whose activity is up-regulated in response to insulin-like growth factor-1 (IGF-1) or insulin stimulation. Whilst at the plasma membrane this PI-PLC is activated and regulated by Gαq/α11 and Gβg subunits, there is yet no evidence that qα/α11 is present within the nuclear compartment, neither GTP-γ-S nor AlF4 can stimulate PI-PLCβ1 activity in isolated nuclei. Here we review the evidence that upon occupancy of type 1 IGF receptor there is translocation to the nucleus of phosphorylated mitogen-activated protein kinase (MAPK) which phosphorylates nuclear PI-PLCβ1 and triggers its signalling, hinting at a separate pathway of regulation depending on the subcellular location of PI-PLCβ1. The difference in the regulation of the activity of PI-PLCβ1mirrors the evidence that nuclear and cytoplasmatic inositides can differ markedly in their signalling capability. Indeed, we do know that agonists which affect nuclear inositol lipid cycle at the nucleus do not stimulate the one at the plasma membrane.
2
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Kinematic regulation of time and frequency domain components of accelerations measured at the tibia during heel-toe running

100%
Sinclair J., Taylor P. J., Hobbs S. J.
Human Movement
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2014
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vol. 15
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issue 1
51-55
EN
Purpose. The transmission of tibial accelerations through the musculoskeletal system may contribute to the aetiology of injuries. Therefore, determining the mechanisms that regulate impact accelerations may have potential clinical significance. This study aimed to determine the influence of lower extremity kinematics on the regulation of both time and frequency domain characteristics of tibial accelerations during running. Methods. Forty participants ran at 4.0 m · s-1 ± 5%. Three-dimensional joint kinematics from the hip, knee and ankle were measured using an eight-camera motion analysis system operating at 250 Hz. Regression analyses treating time and frequency domain tibial acceleration parameters as criterion variables were used to identify lower extremity parameters associated with the passive regulation of impact accelerations. Results. The overall regression model yielded an adj. R2 = 0.13, p 0.01. Knee flexion velocity at footstrike was identified as a significant regulator of tibial accelerations in the time domain. No kinematic variables were identified as significantly related to the frequency domain properties of the signal. Conclusions. The findings of the current investigation suggest that sagittal plane knee flexion velocity at footstrike can regulate the magnitude of impact loading linked to the development of chronic injuries.
3
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Sociological Approach on Sports Ethics in a Context of Social Change

88%
Marivoet S.
Physical Culture and Sport. Studies and Research
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2010
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vol. 49
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issue 1
39-52
EN
In exploring sports ethics as a sociological phenomenon, I have tried to demonstrate how alterations in the nomos of the field of competitive practices (in the sense of Bourdieu), have unexpectedly unleashed a chain of events that have ultimately weakened the ethical principles of modern sport, imposing contradictions upon the way these are manifested in practice. Our theoretical approach to ethics was developed from the contribution of Durkheim, Weber and Elias.The universe of our study was the Portuguese reality during the Democratic state as a case study of the phenomenon. The information collected in our research has required different methods of analysis (qualitative and quantitative) and sources of data (official statistics, news from media, participate observation and interviews).Of the changes that took place in the last quarter of the 20th century in the Portuguese sports field, I have identified the inextricable interdependence of sporting, economic and symbolic dimensions as the main determining factor behind the victory-oriented approach to sporting action, which in turn has led to a radicalization of rival interests and an intensification of competition.As a result of this, there have been changes in the ethos of sporting interaction, weakening the principle of fair play and leading to an increase in practices that undermine it. This has meant that refereeing has become much more difficult, with increased distrust in the fairness of the competition, a situation which is aggravated by cases of corruption and doping. In this context, actors and organizations have become more involved in the ethical regulation of their sport in the Portuguese society. As a result, regulation has become more flexible and open to negotiation, both through institutional channels, and through strategies of pressure and persuasion in the (highly mediatized) public sphere. Thus, contingent solidarities have been strengthened to the detriment of organic solidarities.The growing distrust, together with the dynamics of surveillance and supervision launched in the 1990s, have also contributed to the activation of mechanical solidarities within groups with shared interests, in a context of opposition-confrontation or radicalization. This has been propitious to manifestations of collective violent revolt, and to the institution of forms of premeditated violence between some groups of ultra fans. Consequently, the undermining of ethical regularization has become even more visible, particularly in the field of top-level professional football.In response to the specific nature of the ethical conflicts in the sports figuration, states have intervened at national and European level by enshrining ethical principles in the form of legal provisions, defining systems of sanctions and penalties. This has resulted in a weakening of the autonomy enjoyed by sporting organizations, a principle that ultimately derived from the freedom of sporting associative movement in civil society.
4
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Short-term regulation of the mammalian pyruvate dehydrogenase complex

75%
Strumiło S.
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2005
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vol. 52
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issue 4
759-764
EN
In this minireview the main mechanism of control of mammalian pyruvate dehydrogenase complex (PDHC) activity by phosphorylation-dephosphorylation is presented in the first place. The information recently obtained in several laboratories includes new data about isoforms of the PDH converting enzymes (kinase and phosphatase) and their action in view of short-term regulation of PDHC. Moreover, interesting influence of exogenous thiamine diphosphate (TDP) and some divalent cations, especially Mn2+, on the kinetic parameters of PDHC saturated with endogenous tightly bound TDP, is discussed. This influence causes a shortening of the lag-phase of the catalyzed reaction and a strong decrease of the Km value of PDHC mainly for pyruvate. There are weighty arguments that the effects have an allosteric nature. Thus, besides reversible phosphorylation, also direct manifold increase of mammalian PDHC affinity for the substrate by cofactors seems an important aspect of its regulation.
5
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Isozymes delta of phosphoinositide-specific phospholipase C and their role in signal transduction in the cell.

75%
Ochocka A.-M., Pawelczyk T.
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2003
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vol. 50
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issue 4
1097-1110
EN
Phospholipase C (PLC, EC 3.1.4.11) is an enzyme crucial for the phosphoinositol pathway and whose activity is involved in eukaryotic signal transduction as it generates two second messengers: diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). There are four major types of phospholipase C named: β, γ, δ and the recently discovered ε, but this review will focus only on the recent advances for the γ isozymes of PLC. So far, four d isozymes (named γ1-4) have been discovered and examined. They differ with regard to cellular distribution, activities, biochemical features and involvement in human ailments.
6
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Filamenty cienkie i mikrofilamenty - funkcjonalne kompleksy aktyny z tropomiozyną

63%
Moraczewska J.
Kosmos
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2018
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vol. 67
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issue 1
31-41
PL
Aktyna jest uniwersalnym białkiem o strukturze dobrze zachowanej w toku ewolucji. W komórkach aktyna istnieje w równowadze pomiędzy formą monomeryczną i filamentową. Pomimo zachowanej w toku ewolucji struktury, aktyna pełni zdumiewająco wiele różnorodnych funkcji. Jest to możliwe dzięki zdolności aktyny do oddziaływania z wieloma białkami, wśród których znajdują się motory miozynowe oraz białka regulujące dynamiczną polimeryzację i depolimeryzację aktyny. Nadrzędnymi regulatorami filamentów aktynowych są tropomiozyny, rodzina superhelikalnych białek, które polimeryzują wzdłuż filamentowej aktyny, dzięki czemu stabilizują filamenty zapobiegając ich depolimeryzacji oraz kontrolują dostęp i aktywność białek wiążących aktynę. Tropomiozyny działają jako "stróże" filamentu, którzy kontrolują oddziaływania aktyny, co prowadzi do segregacji białek wiążących aktynę do swoistych przedziałów komórkowych gdzie białka te realizują określone funkcje komórkowe. W artykule zostały omówione zależne od tropomiozyny mechanizmy regulacji oddziaływań aktyny z niektórymi miozynami oraz z Arp2/3 i kofiliną - białkami, które inicjują rozgałęzianie, polimeryzację i depolimeryzację filamentów aktynowych.
EN
Actin is a universal protein highly conserved in evolution. In cells, actin exists in equilibrium between a monomeric and filamentous form. In spite of a conservative structure, actin plays amazingly versatile functions. This is possible due to its interactions with numerous actin-binding proteins, among them with myosin motors and proteins regulating dynamic polymerization and depolymeriation of actin. Tropomyosins, superhelical proteins, which polymerize along the filament and stabilize actin by preventing its depolymerization, are superior actin filament regulators. Tropomyosins control the access and activity of various actin-binding proteins. Tropomyosins act thus as actin “gate-keepers” which control actin interactions leading to the segregation of actin-binding proteins into specific cell compartments where they perform specific cellular functions. This article discusses tropomyosin-dependent mechanisms of regulation of actin interactions with some myosins as well as Arp2/3 and cofilin - the proteins, which initiate branching, polymerization and depolymerization of actin filaments.
7
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Modyfikacje potranslacyjne aktyny

63%
Rędowicz M.
Kosmos
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2018
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vol. 67
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issue 1
43-55
PL
Aktyna, komponent cytoszkieletu komórek eukariotycznych, to jedno z białek najistotniejszych dla funkcjonowania organizmów i najlepiej zachowanych w toku ewolucji. Ta globularna cząsteczka o masie cząsteczkowej około 42,3 kDa występuje zarówno w formie monomerycznej, jak i spolimeryzowanej (filamenty), a zdolność do dynamicznej reorganizacji aktyny jest niezbędna dla życia komórki. Przejście pomiędzy obiema formami jest możliwe dzięki precyzyjnej w czasie i przestrzeni, dynamicznej regulacji organizacji aktyny przez szereg białek wiążących się zarówno z monomerami, jak i filamentami aktyny. Istotnym czynnikiem wpływającym na stopień spolimeryzowania aktyny są także liczne modyfikacje potranslacyjne tego białka. Niniejszy artykuł przeglądowy jest poświęcony omówieniu tego obszernego i wciąż mało poznanego zagadnienia, a w szczególności opisowi jakim modyfikacjom ulega aktyna i w jaki sposób modyfikacje te wpływają na strukturę i funkcje tego wyjątkowego białka.
EN
Actin, a constituent of the cytoskeleton of eukaryotic cells, is one of the most important as well as best evolutionary conserved proteins. This globular protein with molecular mass of ~42.3 kDa exists in the cell both in the monomeric and filamentous form, and ability to undergo dynamic reorganization of these two forms is absolutely crucial for cell survival. The monomer-filament transition, precisely controlled in time and space, is possible due to interaction of actin with a panoply of proteins binding to either monomeric or filamentous actin. Yet another factor is affecting actin organization, namely numerous posttranslational modifications. This review article is devoted to presentation of this broad and still unrecognized topic with emphasis on description of the type of actin modifications and how they affect actin structure and function.
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