CELL MEMBRANE CONSTITUENTS CONCERNED WITH TRANSPORT MECHANISMS

1964 ◽  
Vol 42 (6) ◽  
pp. 971-988 ◽  
Author(s):  
L. S. Wolfe
Keyword(s):  
Cell Membrane ◽  
Biological Membrane ◽  
Transport Processes ◽  
Neuronal Membrane ◽  
Red Cell ◽  
Transport Mechanisms ◽  
Red Cell Membrane ◽  
Membrane Atpase ◽  
Entire Cell ◽  
And Control

The biological membrane is a multiphasic, polyionic, regionally differentiated structure, the constituents of which are closely linked to the physiological and metabolic processes of the entire cell. Knowledge of the types of molecules, their orientation, and the relative importance of them for transport processes is still very fragmentary. The information at present available on the composition of the protoplast membrane, the red cell membrane, and the neuronal membrane is brought together and discussed in terms of the possible role in transport processes. A labile phosphate attached to protein or specific phosphatides or shared between them as a lipo-phosphoprotein complex is suggested as the intermediate in the active transport of sodium. The rapid phosphorylation of these constituents by ATP through the activity of membrane ATPase and their subsequent dephosphorylation could lead to rhythmic transitions in the configuration of membrane proteins and control active cation transport.

scholarly journals CO2 and HCO3- Permeability of the Rat Liver Mitochondrial Membrane

2016 ◽  
Vol 39 (5) ◽  
pp. 2014-2024 ◽  
Author(s):  
Mariela Arias-Hidalgo ◽  
Jan Hegermann ◽  
Georgios Tsiavaliaris ◽  
Fabrizio Carta ◽  
Claudiu T. Supuran ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Mitochondrial Membrane ◽  
Gas Permeability ◽  
Alternative Pathway ◽  
Biological Membrane ◽  
Red Cell ◽  
Inner Mitochondrial Membrane ◽  
Red Cell Membrane ◽  
The Matrix ◽  
Rat Livers

Background/Aims: Across the mitochondrial membrane an exceptionally intense exchange of O2 and CO2 occurs. We have asked, 1) whether the CO2 permeability, PM,CO2, of this membrane is also exceptionally high, and 2) whether the mitochondrial membrane is sufficiently permeable to HCO3- to make passage of this ion an alternative pathway for exit of metabolically produced CO2. Methods: The two permeabilities were measured using the previously published mass spectrometric 18O exchange technique to study suspensions of mitochondria freshly isolated from rat livers. The mitochondria were functionally and morphologically in excellent condition. Results: The intramitochondrial CA activity was exclusively localized in the matrix. PM,CO2 of the inner mitochondrial membrane was 0.33 (SD ± 0.03) cm/s, which is the highest value reported for any biological membrane, even two times higher than PM,CO2 of the red cell membrane. PM,HCO3- was 2· 10-6 (SD ± 2· 10-6) cm/s and thus extremely low, almost 3 orders of magnitude lower than PM,HCO3- of the red cell membrane. Conclusion: The inner mitochondrial membrane is almost impermeable to HCO3- but extremely permeable to CO2. Since gas channels are absent, this membrane constitutes a unique example of a membrane of very high gas permeability due to its extremely low content of cholesterol.

The Wellcome Trust Lecture: Mechanisms of molecular trafficking in malaria

Parasitology ◽  
1988 ◽  
Vol 96 (S1) ◽  
pp. S57-S81 ◽  
Author(s):  
I. W. Sherman
Keyword(s):  
Amino Acids ◽  
Cell Membrane ◽  
Antimalarial Drugs ◽  
Transport Systems ◽  
Red Cell ◽  
Transport Mechanisms ◽  
Red Cell Membrane ◽  
Sodium Potassium ◽  
Future Studies ◽  
Striking Increase

SUMMARYThe asexual stages ofPlasmodiumliving within the erythrocyte result in growth-related changes in the permeability properties of the red cell for substances such as glucose, amino acids, purine nucleosides, sodium, potassium, calcium, zinc, iron and several antimalarial drugs such as chloroquine, amodiaquine and mefloquine. In most cases such changes do not appear to be due to a modification in the affinity or specificity of red cell transporters; indeed, for most substances the membrane-associated transporters are either unaffected or are partially inactivated. In malaria-infected erythrocytes, where a striking increase in influx has been observed, it has been attributed to the insertion of parasite-encoded transporters into the red cell membrane or the formation of aqueous leaks and/or pores. Leak formation, in the vast majority of cases, does not appear to be dependent on the insertion of plasmodial proteins into the red cell membrane. However, since the data presently available are less than satisfactory for discriminating amongst the various possible transport mechanisms future studies will require painstaking efforts and carefully controlled conditions to discriminate amongst the various transport systems which are operational in the malaria-infected red cell and the parasite.

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