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The Na + /K +-ATPase, as well as effects of diffusion of the involved ions, are major mechanisms to maintain the resting potential across the membranes of animal cells.. The relatively static membrane potential of quiescent cells is called the resting membrane potential (or resting voltage), as opposed to the specific dynamic electrochemical phenomena called action potential and graded ...
A low resolution structure from 2D crystals of the PM H +-ATPase from Neurospora crassa is, as of medio 2011, the only structural information on the fungal H +-ATPase. [3] For the plant counterpart, a crystal structure of the AHA2 PM H +-ATPase from Arabidopsis thaliana has been obtained from 3D crystals with a resolution of 3.6 Å. [4]
Hyperpolarization is a change in a cell's membrane potential that makes it more negative. Cells typically have a negative resting potential, with neuronal action potentials depolarizing the membrane. When the resting membrane potential is made more negative, it increases the minimum stimulus needed to surpass the needed threshold.
For example, the resting potential in daylight-adapted blowfly (Calliphora vicina) photoreceptors can be as high as -30 mV. [40] This elevated membrane potential allows the cells to respond very rapidly to visual inputs; the cost is that maintenance of the resting potential may consume more than 20% of overall cellular ATP. [41]
Afterhyperpolarization, or AHP, is the hyperpolarizing phase of a neuron's action potential where the cell's membrane potential falls below the normal resting potential. This is also commonly referred to as an action potential's undershoot phase. AHPs have been segregated into "fast", "medium", and "slow" components that appear to have distinct ...
Plasma membranes exhibit electrochemical polarity through establishment and maintenance of a resting membrane potential. Cells with polarized plasma membranes must buffer and adequately distribute certain ions, such as sodium (Na + ), potassium (K + ), calcium (Ca 2+ ), and chloride (Cl − ) to establish and maintain this polarity.
The sodium–hydrogen antiporter or sodium–proton exchanger (Na+/H+ exchanger or NHX) is a membrane protein that transports Na + into the cell, and H + out of the ...
Diagram of the Na +-K +-ATPase. Since the ions are charged, they cannot pass through cellular membranes via simple diffusion. Two different mechanisms can transport the ions across the membrane: active or passive transport. [citation needed] An example of active transport of ions is the Na +-K +-ATPase (NKA).