Implications of Metabolic Compartmentation in Prokaryotic Cells

1986 ◽  
pp. 121-129
Author(s):  
V. Moses
Keyword(s):  
Metabolic Compartmentation

Metabolic Compartmentation in Living Cells: Structural Association of Aldolase

1997 ◽  
Vol 237 (2) ◽  
pp. 445-451 ◽  
Author(s):  
Jian Wang ◽  
Dean R. Tolan ◽  
Len Pagliaro
Keyword(s):  
Living Cells ◽  
Metabolic Compartmentation ◽  
Structural Association

scholarly journals Channelling of intermediates in the biosynthesis of phosphatidylcholine and phosphatidylethanolamine in mammalian cells

1998 ◽  
Vol 334 (3) ◽  
pp. 511-517 ◽  
Author(s):  
Bellinda A. BLADERGROEN ◽  
Math J. H. GEELEN ◽  
A. Ch. Pulla REDDY ◽  
Peter E. DECLERCQ ◽  
Lambert M. G. VAN GOLDE
Keyword(s):  
Staphylococcus Aureus ◽  
Mammalian Cells ◽  
Glioma Cells ◽  
Rat Hepatocytes ◽  
Cell Types ◽  
General Phenomenon ◽  
Rat Glioma ◽  
Permeabilized Cells ◽  
Metabolic Compartmentation ◽  
Choline Incorporation

Previous studies with electropermeabilized cells have suggested the occurrence of metabolic compartmentation and Ca2+-dependent channeling of intermediates of phosphatidylcholine (PC) biosynthesis in C6 rat glioma cells. With a more accessible permeabilization technique, we investigated whether this is a more general phenomenon also occurring in other cell types and whether channeling is involved in phosphatidylethanolamine (PE) synthesis as well. C6 rat glioma cells, C3H10T½ fibroblasts and rat hepatocytes were permeabilized with Staphylococcus aureus α-toxin, and the incorporation of the radiolabelled precursors choline, phosphocholine (P-choline), ethanolamine and phosphoethanolamine (P-EA) into PC and PE were measured both at high and low Ca2+ concentrations. In glioma cells, permeabilization at high Ca2+ concentration did not affect [14C]choline or [14C]P-choline incorporation into PC. However, reduction of free Ca2+ in the medium from 1.8 mM to < 1 nM resulted in a dramatic increase in [14C]P-choline incorporation into permeabilized cells, whereas [14C]choline incorporation remained unaffected. Also, in fibroblasts, reduction of extracellular Ca2+ increased [14C]P-choline and [14C]P-EA incorporation into PC and PE respectively. In hepatocytes, a combination of α-toxin and low Ca2+ concentration severely impaired [14C]choline incorporation into PC. Therefore, α-toxin-permeabilized hepatocytes are not a good model in which to study channeling of intermediates in PC biosynthesis. In conclusion, our results indicate that channeling is involved in PC synthesis in glioma cells and fibroblasts. PE synthesis in fibroblasts is also at least partly dependent on channeling.

scholarly journals Molecular System Bioenergics of the Heart: Experimental Studies of Metabolic Compartmentation and Energy Fluxes versus Computer Modeling

2011 ◽  
Vol 12 (12) ◽  
pp. 9296-9331 ◽  
Author(s):  
Mayis Aliev ◽  
Rita Guzun ◽  
Minna Karu-Varikmaa ◽  
Tuuli Kaambre ◽  
Theo Wallimann ◽  
...  
Keyword(s):  
Computer Modeling ◽  
Molecular System ◽  
Experimental Studies ◽  
Energy Fluxes ◽  
Metabolic Compartmentation

scholarly journals Endogenous calcium in sickle cells does not activate polyphosphoinositide phospholipase C

1988 ◽  
Vol 254 (1) ◽  
pp. 161-169 ◽  
Author(s):  
M D Rhoda ◽  
J C Sulpice ◽  
P Gascard ◽  
F Galacteros ◽  
F Giraud
Keyword(s):  
Phospholipase C ◽  
Sickle Cell Anaemia ◽  
Total Population ◽  
Original Method ◽  
Sickle Cells ◽  
Metabolic Compartmentation ◽  
Dense Cell ◽  
Lipid Kinases ◽  
32P Incorporation ◽  
Phosphatidylinositol 4

Sickle-cell-anaemia erythrocytes (SS cells) are known to have a high Ca2+ content (particularly the dense cell fraction) and to take up Ca2+ on deoxygenation. It has been reported that this high Ca2+ was responsible for the activation of the Ca2+-dependent K+ loss, and of the Ca2+-sensitive polyphosphoinositide phospholipase C (PIC) in dense SS cells. We found that, either in the total population of SS cells or in the light or dense fractions, the content of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] was not changed, whereas that of phosphatidylinositol 4-phosphate was increased and that of phosphatidic acid (PtdOH) was decreased compared with normal (AA) erythrocytes. Deoxygenation-induced Ca2+ entry into SS cells did not change the concentration or, in 32P-prelabelled cells, the radioactivity of polyphosphoinositides and PtdOH. It also failed to induce the formation of inositol 1,4,5-trisphosphate, the product of PtdIns(4,5)P2 hydrolysis by PIC, which was measured by an original method using ion-pair reverse-phase h.p.l.c. Thus there was no evidence of an endogenous Ca2+ effect on the PIC activity in SS cells, in agreement with the demonstration that the excess Ca2+ in SS cells is compartmentalized into internal vesicles and unavailable as free Ca2+. The 32P incorporation in polyphosphoinositides and PtdOH was markedly higher in SS than in AA cells, but this increase was the same in both dense and light SS cells. The increase in the turnover of these phospholipids in SS cells is consistent either with an activation of the lipid kinases and phosphatases or with perturbation in the metabolic compartmentation of these lipids.

scholarly journals Appendix: Mathematical approaches to the evaluation of the flux of γ-aminobutyrate in brain tissue in vitro

1970 ◽  
Vol 116 (3) ◽  
pp. 461-467 ◽  
Author(s):  
B. J. Hammond ◽  
T. Julian ◽  
Y. Machiyama ◽  
R. Balázs
Keyword(s):  
Computer Simulation ◽  
Tricarboxylic Acid Cycle ◽  
Preceding Paper ◽  
Experimental Results ◽  
Simulation Methods ◽  
Metabolic Compartmentation ◽  
A Value ◽  
Time Courses ◽  
Cortex Slices

In the preceding paper (Balázs, Machiyama, Hammond, Julian & Richter, 1970) the flux of γ-aminobutyrate (GABA) was found, in guinea-pig brain-cortex slices incubated in glucose–saline medium, to represent about 10% of the total tricarboxylic acid cycle flux, as opposed to other estimates, which are as high as 40%. However, the latter value was deduced from experimental results by methods that made no allowance for the metabolic compartmentation of glutamate: a mathematical investigation was therefore undertaken to show that this omission necessarily leads to an overestimation of GABA flux. The magnitude of this over-estimation was shown by computer simulation methods to be of such an order as to bring the corrected value into agreement with the lower value. Computer simulation methods were also used to evaluate the GABA flux from the experimental results presented by Balázs et al. (1970) and a value of 0.0315μmol/min per g wet wt. was obtained. This value was also shown to be consistent, in the simulated system, with the experimentally observed time-courses for the radioactivity and quantity of aspartate. Since there is now evidence that GABA is itself a metabolically compartmented intermediate this possibility was considered mathematically, but it was found that in this case the assumption of compartmentation had little effect upon the value of GABA flux deduced on the basis of GABA homogeneity.

scholarly journals Regulatory signals in messenger RNA: determinants of nutrient–gene interaction and metabolic compartmentation

1998 ◽  
Vol 80 (4) ◽  
pp. 307-321
Author(s):  
John E. Hesketh ◽  
M. Helena Vasconcelos ◽  
Giovanna Bermano
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Mrna Stability ◽  
Transcriptional Control ◽  
Regulation Of Gene Expression ◽  
Untranslated Regions ◽  
Nutritional Requirements ◽  
Control Of Gene Expression ◽  
Metabolic Compartmentation ◽  
Post Transcriptional Regulation

Nutrition has marked influences on gene expression and an understanding of the interaction between nutrients and gene expression is important in order to provide a basis for determining the nutritional requirements on an individual basis. The effects of nutrition can be exerted at many stages between transcription of the genetic sequence and production of a functional protein. This review focuses on the role of post-transcriptional control, particularly mRNA stability, translation and localization, in the interactions of nutrients with gene expression. The effects of both macronutrients and micronutrients on regulation of gene expression by post-transcriptional mechanisms are presented and the post-transcriptional regulation of specific genes of nutritional relevance (glucose transporters, transferrin, selenoenzymes, metallothionein, lipoproteins) is described in detail. The function of the regulatory signals in the untranslated regions of the mRNA is highlighted in relation to control of mRNA stability, translation and localization and the importance of these mRNA regions to regulation by nutrients is illustrated by reference to specific examples. The localization of mRNA by signals in the untranslated regions and its function in the spatial organization of protein synthesis is described; the potential of such mechanisms to play a key part in nutrient channelling and metabolic compartmentation is discussed. It is concluded that nutrients can influence gene expression through control of the regulatory signals in these untranslated regions and that the post-transcriptional regulation of gene expression by these mechanisms may influence nutritional requirements. It is emphasized that in studies of nutritional control of gene expression it is important not to focus only on regulation through gene promoters but also to consider the possibility of post-transcriptional control.

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