1. Functional G-protein heterotrimers are associated with vesicles of putative glutamatergic terminals: implications for regulation of transmitter uptake
- Author
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Ole Petter Ottersen, Gudrun Ahnert-Hilger, Karsten Spicher, Bernd Nümberg, Shigeo Takamori, Sandra Winter, Petter Laake, Elizabeth E. Bellocchio, Ingrid Pahner, and Markus Höltje
- Subjects
GABA Plasma Membrane Transport Proteins ,G protein ,Immunoelectron microscopy ,Protein subunit ,Vesicular glutamate transporter 1 ,Presynaptic Terminals ,Vesicular Transport Proteins ,Glutamic Acid ,Organic Anion Transporters ,Biology ,Synaptic Transmission ,Synaptic vesicle ,Cellular and Molecular Neuroscience ,Antibody Specificity ,GTP-Binding Proteins ,Cerebellum ,Heterotrimeric G protein ,Animals ,Microscopy, Immunoelectron ,Molecular Biology ,gamma-Aminobutyric Acid ,Neurons ,Membrane Proteins ,Membrane Transport Proteins ,Cell Biology ,Immunohistochemistry ,Rats ,Cell biology ,Vesicular transport protein ,Vesicular Glutamate Transport Protein 1 ,Synaptic plasticity ,Vesicular Glutamate Transport Protein 2 ,biology.protein ,Synaptic Vesicles ,Carrier Proteins - Abstract
Changes in the vesicular transmitter content modulate synaptic strength and may contribute to synaptic plasticity. Several transporters mediating transmitter uptake into small synaptic vesicles (SSVs) have been identified but their regulation is largely unknown. Here we show by quantitative immunoelectron microscopy that the heterotrimeric G-protein subunits Galphao(2), Galpha(q/11), Gbeta(2), and Ggamma(7) are associated with vesicle-containing areas in terminals of cerebellar parallel fibers. These terminals also contain the vesicular glutamate transporter 1 (VGLUT1). In contrast, SSVs of climbing fiber terminals that contain VGLUT2 express one of the Gbeta-subunits Gbeta(1), Gbeta(3), or Gbeta(4), Ggamma(7), and one Galpha-subunit, probably Galphao(2). Glutamate uptake into cerebellar SSVs was inhibited by more than 50% by GMppNp, an activator of G proteins. Thus, vesicle populations with different subtypes of vesicular glutamate transporters contain functional G proteins with distinct subunit profiles. Heterotrimeric G proteins may play an important role in the control of vesicular filling.
- Published
- 2003
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