The presynaptic CaV2.2 channel-transmitter release site core complex
Rajesh Khanna1, Qi Li, Joerg Bewersdorf
1Genetics and Development Division, Toronto Western Research Institute, 399 Bathurst Street, Toronto, ON, Canada M5T 2S8.
The European Journal of Neuroscience
|August 10, 2007
Summary
Calcium channel CaV2.2 forms a complex with multiple proteins at transmitter release sites. This study identifies key associated proteins, revealing CaV2.2 as a core component of the vesicle-fusion machinery.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- Calcium channel CaV2.2 is crucial for neurotransmitter release at presynaptic terminals.
- The precise molecular composition of the CaV2.2 complex at transmitter release sites (TRS) is not fully understood.
- Understanding this complex is vital for comprehending synaptic transmission regulation.
Purpose of the Study:
- To identify proteins associated with CaV2.2 channels at presynaptic TRS.
- To determine the proximity and binding strength of these associated proteins to CaV2.2.
- To elucidate the role of the CaV2.2 complex in the vesicle-fusion machinery.
Main Methods:
- Immunoprecipitation using an anti-CaV2.2 antibody (Ab571) to isolate CaV2.2 clusters.
- Quantitative staining covariance analysis (ICA/ICQ) to assess in situ co-localization.
- High-NaCl dissociation challenge (fractional recovery method) to evaluate in vitro binding affinity.
Main Results:
- CaV2.2 clusters co-precipitated with several TRS proteins, including NSF, RIM, spectrin, Munc18, VAMP, and others.
- In situ covariance analysis revealed a specific order of association with CaV2.2 (NSF>RIM>spectrin>Munc18>VAMP).
- Fractional recovery analysis indicated the tightest binding proteins to CaV2.2 were VAMP and actin, followed by tubulin, NSF, Munc18, and syntaxin 1.
Conclusions:
- The CaV2.2 channel cluster is an integral part of a larger multimolecular complex at the presynaptic terminal.
- This complex functions as a vesicle-fusion module, forming the core of the transmitter release site.
- The findings provide a molecular framework for understanding CaV2.2's role in synaptic exocytosis.
Related Concept Videos
01:26Fusion of Secretory Vesicles with the Plasma Membrane
Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
01:26Chemical Synapses
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
01:26Chemical Synapses
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
01:30Ligand-Gated Ion Channel Receptor: Gating Mechanism
Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...
01:28Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
01:12Synaptic Signaling
Neurons communicate at synapses, or junctions, to excite or inhibit the activity of other neurons or target cells, such as muscles. Synapses may be chemical or electrical.