title: Synaptic vesicles contain an ATP-dependent proton pump and show 'knob-like' protrusions on their surface.
abstract: Synaptic vesicles from guinea pig brain were highly purified by chromatography on Sephacryl S 1000. They were associated with a Mg-ATPase which could be solubilized with dichloromethane from vesicle membranes, and which elutes upon gel filtration with a mol. wt. approximately 300 kd. Vesicles accumulate [14C]methylamine in the presence of external ATP, indicating an ATP-dependent proton pump. Electron microscopy using a quick freeze, deep etch, rotary shadowing technique showed characteristic 'knob-like' protrusions on the surface of the vesicle. We suggest that these protrusions represent part of a proton ATPase which may be necessary for packaging of neurotransmitter into synaptic vesicles.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000648:ultrastructure; D017301:Ca(2+) Mg(2+)-ATPase; D006168:Guinea Pigs; D011522:Protons; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D011522:Protons; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase