Editing Cilium (section)

===Transition zone===
To achieve its distinct composition, the proximal-most region of the cilium consists of a '''transition zone''', also known as the '''ciliary gate''', that controls the entry and exit of proteins to and from the cilium.<ref>{{Cite journal|last1=Garcia|first1=Galo|last2=Raleigh|first2=David R.|last3=Reiter|first3=Jeremy F.|date=23 April 2018|title=How the Ciliary Membrane Is Organized Inside-Out to Communicate Outside-In|journal=Current Biology|volume=28|issue=8|pages=R421–R434|doi=10.1016/j.cub.2018.03.010|issn=1879-0445|pmc=6434934|pmid=29689227|bibcode=2018CBio...28.R421G }}</ref><ref>{{Cite journal|last1=Garcia-Gonzalo|first1=Francesc R.|last2=Reiter|first2=Jeremy F.|date=2017-02-01|title=Open Sesame: How Transition Fibers and the Transition Zone Control Ciliary Composition|journal=Cold Spring Harbor Perspectives in Biology|volume=9|issue=2|pages=a028134|doi=10.1101/cshperspect.a028134|issn=1943-0264|pmc=5287074|pmid=27770015}}</ref><ref>{{Cite journal|last1=Gonçalves|first1=João|last2=Pelletier|first2=Laurence|date=April 2017|title=The Ciliary Transition Zone: Finding the Pieces and Assembling the Gate|journal=Molecules and Cells|volume=40|issue=4|pages=243–253|doi=10.14348/molcells.2017.0054|issn=0219-1032|pmc=5424270|pmid=28401750}}</ref> At the transition zone, Y-shaped structures connect the ciliary membrane to the underlying axoneme. Control of selective entry into cilia may involve a sieve-like function of transition zone. Inherited defects in components of the transition zone cause ciliopathies, such as Joubert syndrome. Transition zone structure and function is conserved across diverse organisms, including vertebrates, ''[[Caenorhabditis elegans]]'', ''[[Drosophila melanogaster]]'' and ''[[Chlamydomonas reinhardtii]]''. In mammals, disruption of the transition zone reduces the ciliary abundance of membrane-associated ciliary proteins, such as those involved in [[Hedgehog signaling pathway|Hedgehog signal transduction]], compromising Hedgehog-dependent embryonic development of digit number and central nervous system patterning.