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 (Ca{{sup|2+}}) which extend in a plume a few tens of nanometres from the channel pore.<ref name="Wang 2015">{{cite journal |last1=Wang |first1=Lu-Yang |last2=Augustine |first2=George J. |title=Presynaptic nanodomains: a tale of two synapses |journal=Frontiers in Cellular Neuroscience |date=26 January 2015 |volume=8 |pages=455 |doi=10.3389/fncel.2014.00455 |pmid=25674049 |pmc=4306312|doi-access=free }}</ref> 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 {{cvt|100|nm}}, which allows rapid signalling.<ref name="Eggerman 2011">{{cite journal |last1=Eggermann |first1=Emmanuel |last2=Bucurenciu |first2=Iancu |last3=Goswami |first3=Sarit Pati |last4=Jonas |first4=Peter |title=Nanodomain coupling between Ca{{sup|2+}} channels and sensors of exocytosis at fast mammalian synapses |journal=Nature Reviews. Neuroscience |date=20 December 2011 |volume=13 |issue=1 |pages=7–21 |doi=10.1038/nrn3125 |pmid=22183436 |pmc=3617475}}</ref> 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.<ref name="Stanley 2016"/> The nanodomain signal collapses just as quickly when the calcium channel closes, as the ions rapidly diffuse away from the pore.<ref name="Stanley 2016">{{cite journal |last1=Stanley |first1=Elise F. |title=The nanophysiology of fast transmitter release |journal=Trends in Neurosciences |date=March 2016 |volume=39 |issue=3 |pages=183–197 |doi=10.1016/j.tins.2016.01.005 |pmid=26896416|doi-access=free }}{{open access}}</ref> Formation of a nanodomain signal requires the influx of only approximately 1000 calcium ions.<ref>{{cite book |last1=Filadi |first1=Riccardo |last2=Basso |first2=Emy |last3=Lefkimmiatis |first3=Konstantinos |last4=Pozzan |first4=Tullio |title=Membrane Dynamics and Calcium Signaling |chapter=Beyond Intracellular Signaling: The Ins and Outs of Second Messengers Microdomains |series=Advances in Experimental Medicine and Biology |date=2017 |volume=981 |pages=279–322 |doi=10.1007/978-3-319-55858-5_12 |pmid=29594866 |chapter-url=https://books.google.com/books?id=oqFTDwAAQBAJ&pg=PA285|isbn=9783319558585 }}</ref>
Coupling distances greater than {{cvt|100|nm}}, mediated by a larger number of channels, are referred to as microdomains.<ref name="Eggerman 2011"/> nanodomain
== Properties ==
Nanodomain signals are thought to improve the temporal precision of fast exocytosis of vesicles due to two specific properties:<ref name="Oheim 2006">{{cite journal |last1=Oheim |first1=Martin |last2=Kirchhoff |first2=Frank |last3=Stühmer |first3=Walter |title=Calcium microdomains in regulated exocytosis |journal=Cell Calcium |date=2006 |volume=40 |issue=5–6 |pages=423–39 |doi=10.1016/j.ceca.2006.08.007 |pmid=17067670}}</ref> * The peak concentration of calcium ions will be reached incredibly quick (within a microsecond) and maintained as long as the channel is open. * Closure of the channel leads to a rapid collapse of the domain due to lateral diffusion away from the pore (the site of entry). The lateral diffusion of microdomains additionally depends on the action of fast endogenous buffers (which remove the calcium and transport it away from the active zone).
Single channels are able to cause vesicular release, however, the cooperativity of different calcium channels is synapse-specific. The release driven by a single calcium ion channel minimizes the total calcium ion influx, overlapping domains can provide greater reliability and temporal fidelity.<ref name="Oheim 2006"/>
==References== {{Reflist}}
Category:Molecular biology
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