Editing Signal transduction (section)

===Osmolarity===
{{Main|Osmoreceptor}}
Cellular and systemic control of [[osmotic pressure]] (the difference in [[osmolarity]] between the [[cytosol]] and the extracellular medium) is critical for homeostasis. There are three ways in which cells can detect osmotic stimuli: as changes in macromolecular crowding, ionic strength, and changes in the properties of the plasma membrane or cytoskeleton (the latter being a form of mechanotransduction).<ref name="Pedersen">{{Cite journal |vauthors=Pedersen SF, Kapus A, Hoffmann EK |date=September 2011 |title=Osmosensory mechanisms in cellular and systemic volume regulation |journal=Journal of the American Society of Nephrology |volume=22 |issue=9 |pages=1587–97 |doi=10.1681/ASN.2010121284 |pmid=21852585 |doi-access=free}}</ref> These changes are detected by proteins known as osmosensors or osmoreceptors. In humans, the best characterised osmosensors are [[transient receptor potential channel]]s present in the [[primary cilium]] of human cells.<ref name="Pedersen" /><ref>{{Cite journal |vauthors=Verbalis JG |date=December 2007 |title=How does the brain sense osmolality? |journal=Journal of the American Society of Nephrology |volume=18 |issue=12 |pages=3056–9 |doi=10.1681/ASN.2007070825 |pmid=18003769 |doi-access=free}}</ref> In yeast, the HOG pathway has been extensively characterised.<ref>{{Cite journal |vauthors=Hohmann S |date=June 2002 |title=Osmotic stress signaling and osmoadaptation in yeasts |journal=Microbiology and Molecular Biology Reviews |volume=66 |issue=2 |pages=300–72 |doi=10.1128/MMBR.66.2.300-372.2002 |pmc=120784 |pmid=12040128}}</ref>