Role of Ca2+in the Electrostatic Stability and the Functional Activity of the Globular Domain of Human C1q†

Biochemistry ◽  
2005 ◽  
Vol 44 (43) ◽  
pp. 14097-14109 ◽  
Author(s):  
Lubka T. Roumenina ◽  
Alexandar A. Kantardjiev ◽  
Boris P. Atanasov ◽  
Patrick Waters ◽  
Mihaela Gadjeva ◽  
...  
Keyword(s):  
Functional Activity ◽  
Globular Domain ◽  
Electrostatic Stability

The role of neurohumours in early embryogenesis

Development ◽  
1970 ◽  
Vol 23 (3) ◽  
pp. 549-569
Author(s):  
G. A. Buznikov ◽  
A. N. Kost ◽  
N. F. Kucherova ◽  
A. L. Mndzhoyan ◽  
N. N. Suvorov ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Functional Activity ◽  
Early Onset ◽  
Active Sites ◽  
Physiological Effect ◽  
Early Embryogenesis ◽  
Dopamine Synthesis ◽  
Direct Involvement ◽  
Misgurnus Fossilis

In previous papers (Buznikov, Chudakova & Zvezdina, 1964; Buznikov, Chudakova, Berdysheva & Vyazmina, 1968) we reported that fertilized eggs of the sea-urchin Strongylocentrotus dröbachiensis synthesized a number of neurohumours, such as serotonin (5-hydroxytryptamine, 5-HT), acetylcholine (ACh), adrenalin (A), noradrenalin (NA) and dopamine. Synthesis of 5-HT was also demonstrated in the fertilized eggs of the loach Misgurnus fossilis and some marine Invertebrata. In experiments with sea-urchin embryos we were able to trace regular changes in the level of 5-HT, ACh, A and NA, related to the first cleavage divisions. This early onset of neurohumour synthesis, as well as regular changes in their level, suggests their direct involvement in the regulation of the first cleavage divisions. The functional activity of neurohumours (M) in adult organisms is realized through their reaction with the active sites of corresponding receptors (R) according to the following equation:The magnitude of the physiological effect under certain conditions is linearly proportional to the number of complexes MR formed (Turpayev, 1962; Ariëns, 1964).

Role of Functional Activity of Phagocytic Mononuclear System in the Formation of Autoprostheses for Angioplasty

2005 ◽  
Vol 140 (2) ◽  
pp. 217-218
Author(s):  
V. A. Chereshnev ◽  
N. V. Tyumentseva ◽  
B. G. Yushkov ◽  
I. G. Danilova ◽  
V. V. Khodakov ◽  
...  
Keyword(s):  
Functional Activity

Abstract 20627: Modulation of Cardiac Sodium Channel by Palmitoylation and Its Association With Cardiac Disease Mutations

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Zifan Pei ◽  
Andy Hudmon ◽  
Theodore R Cummins
Keyword(s):  
Steady State ◽  
Sodium Channel ◽  
Functional Activity ◽  
Site Directed Mutagenesis ◽  
Significant Shift ◽  
Biophysical Properties ◽  
Disease Mutations ◽  
Cardiac Sodium Channel ◽  
Steady State Inactivation

Cardiac sodium channel (Nav1.5) is responsible for the generation and propagation of the cardiac action potential, which underlies cardiac excitability. It can be modified by a variety of post-translational modifications. Palmitoylation is one of the most common post-translational lipid modifications that can dynamically regulate protein life cycle and functional activity. In our study, we identified palmitoylation on Nav1.5 and its alteration in channel biophysical properties. Nav1.5 palmitoylation was identified in both HEK 293 cells stably expressing Nav1.5 and cardiac tissues using acyl-biotin exchange assay. Nav1.5 palmitoylation was inhibited by pre-incubating the cells with the inhibitor 2-Br-Palmitate (2BP, 25uM, 24hrs). Biophysically, 2BP treatment drastically shifted the channel steady-state inactivation to more hyperpolarized voltages, suggesting palmitoylation altering channel functional activity. In addition, four predicted endogenous palmitoylation sites were identified using CSS-Palm 3.0. Site-directed mutagenesis method was used to generate a cysteine removing background of wt Nav1.5 to study the role of predicted sites. Patch clamp analysis of wt and cysteine-removed Nav1.5 revealed a significant change in channel biophysics. 2BP treatment significantly shifted steady-state inactivation of wt Nav1.5 while not affecting cysteine-removed Nav1.5 significantly, indicating the important role of these four cysteine sites in modulating channel palmitoylation. Moreover, several LQT disease mutations were identified to potentially add or remove palmitoylation sites. Further analysis of these disease mutations revealed a significant shift in channel steady-state inactivation and this alteration cannot be seen with the substitution of other residues on the same site, suggesting the specific role of cysteine residue in causing the functional alteration. For the LQT mutation that removes potential palmitoylation site, 2BP treatment did not affect channel biophysical properties, indicating the essential role of this cysteine in channel palmitoylation. These results suggest that palmitoylation on Nav1.5 regulates channel functional activity and its modulation may contribute to new cardiac channelopathies.

scholarly journals Role of Histone N-Terminal Tails and Their Acetylation in Nucleosome Dynamics

2000 ◽  
Vol 20 (19) ◽  
pp. 7230-7237 ◽  
Author(s):  
Violette Morales ◽  
Hélène Richard-Foy
Keyword(s):  
Topoisomerase I ◽  
Globular Domain ◽  
Histone Tail ◽  
Histone Tails ◽  
Nucleosome Dynamics ◽  
Nucleosome Structure ◽  
Left Handed ◽  
Negative Supercoiling ◽  
And Function

ABSTRACT Histone N-terminal tails are central to the processes that modulate nucleosome structure and function. We have studied the contribution of core histone tails to the structure of a single nucleosome and to a histone (H3-H4)2 tetrameric particle assembled on a topologically constrained DNA minicircle. The effect of histone tail cleavage and histone tail acetylation on the structure of the nucleoprotein particle was investigated by analyzing the DNA topoisomer equilibrium after relaxation of DNA torsional stress by topoisomerase I. Removal of the H3 and H4 N-terminal tails, as well as their acetylation, provoked a dramatic change in the linking-number difference of the (H3-H4)2 tetrameric particle, with a release of up to 70% of the negative supercoiling previously constrained by this structure. The (H3-H4)2 tetramers containing tailless or hyperacetylated histones showed a striking preference for relaxed DNA over negatively supercoiled DNA. This argues in favor of a change in tetramer structure that constrains less DNA and adopts a relaxed flat conformation instead of its left-handed conformation within the nucleosome. In contrast neither removal or hyperacetylation of H3 and H4 tails nor removal or hyperacetylation of H2A and H2B N-terminal tails affected the nucleosome structure. This indicates that the globular domain of H2A and H2B is sufficient to stabilize the tailless or the hyperacetylated (H3-H4)2tetramer in a left-handed superhelix conformation. These results suggest that the effect of histone tail acetylation that facilitates transcription may be mediated via transient formation of an (H3-H4)2 tetrameric particle that could adopt an open structure only when H3 and/or H4 tails are hyperacetylated.

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