Nanodomain
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A nanodomain is a nanometer-sized cluster of proteins found in a cell membrane. They are associated with the signal which occurs when a single calcium ion channel opens on a cell membrane, allowing an influx of calcium ions (Ca2+) which extend in a plume a few tens of nanometres from the channel pore.[1] In a nanodomain, the coupling distance, that is, the distance between the calcium-binding proteins which sense the calcium, and the calcium channel, is very small, less than 100 nm (3.9×10−6 in), which allows rapid signalling.[2] The formation of a nanodomain signal is virtually instantaneous following the opening of the calcium channel, as calcium ions move rapidly into the cell along a steep concentration gradient.[3] The nanodomain signal collapses just as quickly when the calcium channel closes, as the ions rapidly diffuse away from the pore.[3] Formation of a nanodomain signal requires the influx of only approximately 1000 calcium ions.[4]
Coupling distances greater than 100 nm (3.9×10−6 in), mediated by a larger number of channels, are referred to as microdomains.[2] nanodomain