Editing Cytoskeleton (section)

==Common features and differences between prokaryotes and eukaryotes==
By definition, the cytoskeleton is composed of proteins that can form longitudinal arrays (fibres) in all organisms. These filament forming proteins have been classified into 4 classes. [[Tubulin]]-like, [[actin]]-like, Walker A cytoskeletal ATPases (WACA-proteins), and [[intermediate filaments]].<ref name="Wickstead2011"/><ref name=gunning />

Tubulin-like proteins are [[tubulin]] in eukaryotes and [[FtsZ]], TubZ, RepX in prokaryotes. Actin-like proteins are [[actin]] in eukaryotes and [[MreB]], [[FtsA]] in prokaryotes. An example of a WACA-proteins, which are mostly found in prokaryotes, is [[MinD]]. Examples for intermediate filaments, which have almost exclusively been found in animals (i.e. eukaryotes) are the [[lamin]]s, [[keratin]]s, [[vimentin]], [[neurofilament]]s, and [[desmin]].<ref name="Wickstead2011"/>

Although tubulin-like proteins share some [[amino acid sequence]] similarity, their equivalence in protein-fold and the similarity in the [[Guanosine triphosphate|GTP]] binding site is more striking. The same holds true for the actin-like proteins and their structure and [[Adenosine triphosphate|ATP]] binding domain.<ref name="Wickstead2011"/><ref name=gunning />

Cytoskeletal proteins are usually correlated with cell shape, DNA segregation and cell division in prokaryotes and eukaryotes. Which proteins fulfill which task is very different. For example, DNA segregation in all eukaryotes happens through use of tubulin, but in prokaryotes either WACA proteins, actin-like or tubulin-like proteins can be used. Cell division is mediated in eukaryotes by actin, but in prokaryotes usually by tubulin-like (often FtsZ-ring) proteins and sometimes ([[Thermoproteota]]) [[ESCRT#ESCRT-III|ESCRT-III]], which in eukaryotes still has a role in the last step of division.<ref name="Wickstead2011"/>