Our neurons use electrical impulses and complex molecular machinery to communicate information throughout our bodies. In order to be ready to transfer the signal when it arrives, the neurons need to maintain high concentrations of sodium on the outside of the membrane and potassium ions on the inside. With each signal transmission, sodium enters the neuron followed by potassium exiting the cell.
This process is mediated by membrane proteins called voltage gated ion channels. voltage-gated ion channels open and close in reaction to changes in membrane voltage when the neuron is at rest, the ion-channels are closed, and the overall concentrations of ions and proteins create a higher potential on the outside to transmit a signal, the neuron creates an action potential
Voltage gated sodium channels, which allow sodium to enter the neuron. then, to counteract the positive charge of the sodium ions, potassium channels start to open allowing potassium ions to exit and potassium channels prime the neuron for the next signal by allowing potassium to exit. sodium concentration is high on the inside and potassium concentration is high on the
Outside the sodium-potassium pump restores the sodium and potassium gradients because the pump moves these ions against their concentration gradients it requires the energy of one atp molecule for each cycle. within the alpha chain, three domains, a, with atp bound in the n site and the transmembrane region open into the cell, the pump binds three sodium ions from the
Cytoplasm. with the help of magnesium co-factor, the adp is cleaved off and the p-site is phosphorylated this leads a conformational change that exposes the the sodium ions to the outside. the sodium ions can then be released, one after another, into the extracellular space. in this ion-empty state, the pump allows the entry of 2 potassium ions. followed by closing of
The extracellular gate and allows the n domain to accept the atp again. as a result of atp binding, the intracellular gate opens, the potassium ions are released into the cytoplasm, the sodium-potassium pump is a key protein working to maintain the sodium-potassium gradients roughly a third of the atp made daily by our cells is spent to power this molecular machine.
Transcribed from video
Neuronal Signaling and Sodium-Potassium Pump (from PDB-101) By RCSBProteinDataBank
