Editing Intermediate filament (section)

{{Short description|Cytoskeletal structure}}
{{Infobox protein family
| Symbol = IF_tail
| Name = Intermediate filament tail domain
| image = PDB 1ifr EBI.jpg
| width =
| caption = Structure of lamin a/c globular domain
| Pfam = PF00932
| Pfam_clan =
| InterPro = IPR001322
| SMART =
| PROSITE = PDOC00198
| MEROPS =
| SCOP = 1ivt
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{Infobox protein family
| Symbol = Filament
| Name = Intermediate filament rod domain
| image = PDB 1gk4 EBI.jpg
| width =
| caption = Human vimentin coil 2b fragment (cys2)
| Pfam = PF00038
| Pfam_clan =
| InterPro = IPR016044
| SMART =
| PROSITE = PDOC00198
| MEROPS =
| SCOP = 1gk7
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{Infobox protein family
| Symbol = Filament_head
| Name = Intermediate filament head (DNA binding) region
| image =
| width =
| caption =
| Pfam = PF04732
| Pfam_clan =
| InterPro = IPR006821
| SMART =
| PROSITE =
| MEROPS =
| SCOP = 1gk7
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{infobox protein
| Name = Peripherin neuronal intermediate filament protein
| caption =
| image =
| width =
| HGNCid = 9461
| Symbol = PRPH
| AltSymbols =NEF4
| EntrezGene = 5630
| OMIM = 170710
| RefSeq = NM_006262.3
| UniProt = P41219
| PDB =
| ECnumber =
| Chromosome = 12
| Arm = q
| Band = 13.12
| LocusSupplementaryData =
}}
{{infobox protein
| Name = Nestin neuronal stem cell intermediate filament protein
| caption =
| image =
| width =
| HGNCid = 7756
| Symbol = NES
| AltSymbols =
| EntrezGene = 10763
| OMIM = 600915
| RefSeq = NP_006608
| UniProt = P48681
| PDB =
| ECnumber =
| Chromosome = 1
| Arm = q
| Band = 23.1
| LocusSupplementaryData =
}}

'''Intermediate filaments''' ('''IFs''') are [[cytoskeleton|cytoskeletal]] structural components found in the cells of [[vertebrate]]s, and many [[invertebrate]]s.<ref name="pmid17551517">{{cite journal | vauthors = Herrmann H, Bär H, Kreplak L, Strelkov SV, Aebi U | title = Intermediate filaments: from cell architecture to nanomechanics | journal = Nature Reviews. Molecular Cell Biology | volume = 8 | issue = 7 | pages = 562–73 | date = July 2007 | pmid = 17551517 | doi = 10.1038/nrm2197 | s2cid = 27115011 }}</ref><ref name="Chang">{{cite journal | vauthors = Chang L, Goldman RD | title = Intermediate filaments mediate cytoskeletal crosstalk | journal = Nature Reviews. Molecular Cell Biology | volume = 5 | issue = 8 | pages = 601–13 | date = August 2004 | pmid = 15366704 | doi = 10.1038/nrm1438 | s2cid = 31835055 }}</ref><ref>{{citation |author=Traub, P. |year=2012  |title=Intermediate Filaments: A Review |publisher=Springer Berlin Heidelberg  |isbn=978-3-642-70230-3 |url=https://books.google.com/books?id=TVLoCAAAQBAJ |page=33}}</ref> Homologues of the IF protein have been noted in an invertebrate, the [[cephalochordate]] ''[[Branchiostoma]]''.<ref name="pmid9804163">{{cite journal | vauthors = Karabinos A, Riemer D, Erber A, Weber K | title = Homologues of vertebrate type I, II and III intermediate filament (IF) proteins in an invertebrate: the IF multigene family of the cephalochordate Branchiostoma | journal = FEBS Letters | volume = 437 | issue = 1–2 | pages = 15–8 | date = October 1998 | pmid = 9804163 | doi = 10.1016/S0014-5793(98)01190-9 | s2cid = 7886395 | doi-access = free | bibcode = 1998FEBSL.437...15K }}</ref>

Intermediate filaments are composed of a family of related [[protein]]s sharing common structural and sequence features.  Initially designated 'intermediate' because their average diameter (10&nbsp;[[Nanometre|nm]]) is between those of narrower [[microfilament]]s (actin) and wider [[myosin]] filaments found in muscle cells, the diameter of intermediate filaments is now commonly compared to [[actin]] microfilaments (7&nbsp;nm) and [[microtubule]]s (25&nbsp;nm).<ref name="pmid17551517"/><ref name="pmid5664223">{{cite journal | vauthors = Ishikawa H, Bischoff R, Holtzer H | title = Mitosis and intermediate-sized filaments in developing skeletal muscle | journal = The Journal of Cell Biology | volume = 38 | issue = 3 | pages = 538–55 | date = September 1968 | pmid = 5664223 | pmc = 2108373 | doi = 10.1083/jcb.38.3.538 }}</ref> Animal intermediate filaments are subcategorized into six types based on similarities in amino acid sequence and [[protein]] structure.<ref name="interfil">{{cite journal | vauthors = Szeverenyi I, Cassidy AJ, Chung CW, Lee BT, Common JE, Ogg SC, Chen H, Sim SY, Goh WL, Ng KW, Simpson JA, Chee LL, Eng GH, Li B, Lunny DP, Chuon D, Venkatesh A, Khoo KH, McLean WH, Lim YP, Lane EB | display-authors = 6 | title = The Human Intermediate Filament Database: comprehensive information on a gene family involved in many human diseases | journal = Human Mutation | volume = 29 | issue = 3 | pages = 351–360 | date = March 2008 | pmid = 18033728 | doi = 10.1002/humu.20652 | s2cid = 20760837 | doi-access = free }}</ref> Most types are [[cytoplasm]]ic, but one type, Type V is a [[nuclear lamin]]. Unlike microtubules, IF distribution in cells shows no good correlation with the distribution of either [[mitochondria]] or [[endoplasmic reticulum]].<ref name="pmid1363623">{{cite journal | vauthors = Soltys BJ, Gupta RS | title = Interrelationships of endoplasmic reticulum, mitochondria, intermediate filaments, and microtubules--a quadruple fluorescence labeling study | journal = Biochemistry and Cell Biology  | volume = 70 | issue = 10–11 | pages = 1174–86 | date = 1992 | pmid = 1363623 | doi = 10.1139/o92-163 }}</ref>