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Introduction to Solid Supported Membrane Based Electrophysiology
Published on: May 11, 2013
pH gradient across the lysosomal membrane generated by selective cation permeability and Donnan equilibrium
Biochimica Et Biophysica Acta
|August 20, 1975
Summary
Lysosomes maintain acidity via Donnan equilibrium and selective proton permeability. This internal acidity is crucial for lysosomal function and cellular processes.
Area of Science:
- Cell Biology
- Biochemistry
- Physiology
Background:
- Lysosomes are vital organelles responsible for cellular degradation.
- Understanding lysosomal pH is critical for comprehending their function.
Purpose of the Study:
- To determine the intralysosomal pH of isolated rat liver lysosomes.
- To investigate the mechanisms maintaining lysosomal acidity.
Main Methods:
- Utilized [14C]methylamine distribution to measure intralysosomal pH.
- Assessed the impact of extralysosomal cation concentration on pH gradient.
- Evaluated lysosomal membrane permeability to various cations.
Main Results:
- Intralysosomal pH was approximately one unit lower than the external medium.
- Cation exchange indicated a Donnan equilibrium, influencing the pH gradient.
- Lysosomal membrane exhibited higher proton permeability compared to other cations.
- Established cation mobility order: H+ > Cs+ > Rb+ > K+ > Na+ > Li+ > Mg2+, Ca2+.
Conclusions:
- Lysosomal acidity is maintained by a Donnan equilibrium due to nondiffusible intralysosomal anions.
- Selective cation permeability of the lysosomal membrane, particularly for protons, contributes to acidity.
- These mechanisms are essential for regulating lysosomal function.
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