Gated Ion Channels. Ahu Karademir Andrei Vasiliev. Contents. General Information Voltage-Gated Ion Channels Ligand-Gated Ion Channels The Acetylcholine Receptor Neurotransmitters Toxin targets. Gated Ion Channels. Another type of membrane transport
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-“Dispose” of the gradients
-Ions flow from high to low concentration
-No energy is used
-If there is no gradient ions will not flow
-Transport of ions and water
-Regulation of electrical
potential across the
Voltage across the cell membrane
Mechanical stimulus, heat (thermal fluctuations)
-3D conformational shape is determined by atomic, electric, and hydrophobic forces
-Have the place for the direct interaction with G proteins and phosphorylation
-Presynaptic terminal and all secretory cells
Ion Flow = Current
nicotine, and so is called the “nicotinic” acetylcholine receptor -nAChR
the resting (closed) ion channel to acetylcholine (ACh)producesthe excited (open) state. Longer exposure leads to desensitization and channel closure.
•Synaptic transmission throughout the nervous system is predominantly
•At the chemical level, the key players include integral membrane
proteins that control signaling
Action Potential opens voltage gated Ca+2 channels
Ca+2 enters the terminal.
Ca+2 initiates vesicular release of
Reserve vesicles are outside the active zone. Synapsins tethers vesicles to the cytoskeleton
Ca+2 activates Ca2+/calmodulin dependent protein kinase
which phosphorylates synapsin I and frees the vesicles.