An ATP-driven proton pump in clathrin-coated vesicles.

Area of Science:

• Cell Biology
• Biochemistry
• Neuroscience

Background:

• Clathrin-coated vesicles are primarily known for their role in intracellular trafficking.
• Proton pumps are essential for various cellular processes, including energy transduction.

Purpose of the Study:

• To investigate potential enzymatic activities of clathrin-coated vesicles.
• To characterize the proton translocation and ATP-exchange capabilities of these vesicles.

Main Methods:

• Purification of clathrin-coated vesicles from bovine brain.
• Assay of ATP-driven proton translocation and 32Pi-ATP exchange.
• Inhibition studies using specific reagents like oligomycin, dicyclohexylcarbodiimide, and N-ethylmaleimide.
• Immunoprecipitation using antibodies against clathrin.

Main Results:

• Clathrin-coated vesicles catalyzed ATP-driven proton translocation and 32Pi-ATP exchange.
• These activities were resistant to oligomycin, unlike those in submitochondrial particles.
• The proton pump activity was concentrated in purified coated vesicle fractions and immunoprecipitated with clathrin.
• Dicyclohexylcarbodiimide and N-ethylmaleimide inhibited the pump, while other inhibitors had no effect.

Conclusions:

• Clathrin-coated vesicles possess an oligomycin-resistant proton pump activity.
• This finding suggests a previously unrecognized role for clathrin-coated vesicles in cellular energy metabolism or ion transport.