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Determinants of clathrin-coated vesicle acidification
The Journal of Biological Chemistry
|December 25, 1983
Summary
The proton-translocating ATPase in brain vesicles uses ATP and requires co-ions like chloride for proton pumping. Its function can be modulated by membrane potential and ion gradients.
Area of Science:
- Biochemistry
- Cell Biology
- Neuroscience
Background:
- Clathrin-coated vesicles play crucial roles in intracellular transport.
- Proton pumps are essential for maintaining cellular pH and driving transport processes.
Purpose of the Study:
- To characterize the ATP specificity and ion-coupling mechanisms of the proton-translocating ATPase in bovine brain clathrin-coated vesicles.
- To investigate the role of co-ions and membrane potential in regulating proton translocation and chloride transport.
Main Methods:
- Biochemical assays to measure ATP hydrolysis and proton translocation.
- Ion transport studies using electrophysiological techniques and ionophores (e.g., valinomycin).
- Vesicle preparation from bovine brain tissue.
Main Results:
- The proton pump exhibits specific ATP requirements.
- Chloride or bromide ions act as essential co-ions to balance the electrogenic proton pumping.
- Proton translocation can occur without chloride if the membrane potential is dissipated.
- Chloride transport is observable independently of proton movement under specific membrane potential conditions.
Conclusions:
- The proton-translocating ATPase is a key component of clathrin-coated vesicle function.
- The activity of this ATPase is tightly regulated by ATP availability, co-ion presence, and membrane potential.
- Understanding these mechanisms provides insights into vesicular transport and cellular energetics.