Editing Chemotaxis (section)

===Receptors===
In general, eukaryotic cells sense the presence of chemotactic stimuli through the use of 7-transmembrane (or serpentine) heterotrimeric [[G protein|G-protein]]-coupled receptors, a class representing a significant portion of the [[genome]].<ref>{{cite journal | vauthors = Kim JY, Haastert PV, Devreotes PN | title = Social senses: G-protein-coupled receptor signaling pathways in Dictyostelium discoideum | journal = Chemistry & Biology | volume = 3 | issue = 4 | pages = 239–243 | date = April 1996 | pmid = 8807851 | doi = 10.1016/s1074-5521(96)90103-9 | doi-access = free }}</ref> Some members of this gene superfamily are used in eyesight ([[rhodopsins]]) as well as in [[olfaction]] (smelling).<ref>{{cite journal | vauthors = Montell C | title = Visual transduction in Drosophila | journal = Annual Review of Cell and Developmental Biology | volume = 15 | issue = 1 | pages = 231–268 | date = November 1999 | pmid = 10611962 | doi = 10.1146/annurev.cellbio.15.1.231 | s2cid = 14193715 }}</ref><ref>{{Cite book | vauthors = Antunes G, Simoes de Souza FM | title = G Protein-Coupled Receptors - Signaling, Trafficking and Regulation | chapter = Olfactory receptor signaling | series = Methods in Cell Biology | volume = 132 | pages = 127–45 | date = 2016 | pmid = 26928542 | doi = 10.1016/bs.mcb.2015.11.003  | isbn = 9780128035955 }}</ref> The main classes of chemotaxis receptors are triggered by:
* Formyl peptides - [[formyl peptide receptor]]s (FPR), 
* [[Chemokines]] - [[chemokine receptor]]s (CCR or CXCR), and 
* [[Leukotrienes]] - [[leukotriene receptor]]s (BLT).<ref>{{cite journal | vauthors = Thomas MA, Kleist AB, Volkman BF | title = Decoding the chemotactic signal | journal = Journal of Leukocyte Biology | volume = 104 | issue = 2 | pages = 359–374 | date = August 2018 | pmid = 29873835 | pmc = 6099250 | doi = 10.1002/JLB.1MR0218-044 }}</ref>
However, induction of a wide set of membrane receptors (e.g., [[cyclic nucleotide]]s, [[amino acids]], [[insulin]], vasoactive peptides) also elicit migration of the cell.<ref>{{cite journal | vauthors = van Haastert PJ, De Wit RJ, Konijn TM | title = Antagonists of chemoattractants reveal separate receptors for cAMP, folic acid and pterin in Dictyostelium | journal = Experimental Cell Research | volume = 140 | issue = 2 | pages = 453–6 | date = August 1982 | pmid = 7117406 | doi = 10.1016/0014-4827(82)90139-2 | s2cid = 27784085 | url = https://pure.rug.nl/ws/files/14539904/1982ExpCellResvHaastert.pdf }}</ref>

====Chemotactic selection====
[[Image:chtxsel.png|right|300 px|<div style="text-align: center;border:none">Chemotactic selection</div>]]
While some chemotaxis receptors are expressed in the surface membrane with long-term characteristics, as they are determined genetically, others have short-term dynamics, as they are assembled ''ad hoc'' in the presence of the ligand.<ref>{{cite book | vauthors = Witzany G, Nowacki M |title=Biocommunication of Ciliates |date=2016 |publisher=Springer |isbn=978-3-319-32211-7 }}{{page needed|date=July 2020}}</ref> The diverse features of the chemotaxis receptors and ligands allows for the possibility of selecting chemotactic responder cells with a simple chemotaxis assay By [[chemotactic selection]], we can determine whether a still-uncharacterized molecule acts via the long- or the short-term receptor pathway.<ref>{{cite book | vauthors = Köhidai L |chapter=Chemotaxis as an Expression of Communication of Tetrahymena |pages=65–82 |chapter-url=https://books.google.com/books?id=KnFBDAAAQBAJ&pg=PA65 |doi=10.1007/978-3-319-32211-7_5 | veditors = Witzany G, Nowacki M |title=Biocommunication of Ciliates |date=2016 |publisher=Springer |isbn=978-3-319-32211-7 }}</ref> The term ''chemotactic selection'' is also used to designate a technique that separates eukaryotic or prokaryotic cells according to their chemotactic responsiveness to selector ligands.<ref>{{cite journal | vauthors = Köhidai L, Csaba G | s2cid = 33755476 | title = Chemotaxis and chemotactic selection induced with cytokines (IL-8, RANTES and TNF-alpha) in the unicellular Tetrahymena pyriformis | journal = Cytokine | volume = 10 | issue = 7 | pages = 481–6 | date = July 1998 | pmid = 9702410 | doi = 10.1006/cyto.1997.0328 }}</ref>{{primary source inline|date=March 2017}}{{primary source inline|date=March 2017}}