PROSITE documentation PDOC51980
Occludin/ELL (OCEL) domain profile


Tight junctions (TJs) are intercellular contacts located in epithelial and endothelial cell layers, which are responsible for the maintenance of the paracellular barrier. This barrier is required to limit paracellular passage of undesirables, like toxins, antigens, and microbes, while permitting vectorial transport of material across the layer. The actual barrier is formed by continuous adhesive strands of transmembrane proteins that interact to seal the paracellular space. The TJ proteins tricellulin and occludin show some similarities. Next to the common central MARVEL domain (see <PS51225>) both contain a C-terminal cytoplasmic coiled-coil (CC) domain that is highly homologous to an important functional domain in the C-terminus of ELL/ELL2 proteins, which are a family of RNA polymerase II (Pol II) transcription factors. This ~110-amino acid occludin/ELL domain, termed the OCEL domain, is necessary for interactions between occludin and ZO-1, actin, and multiple kinases and may also mediate homotypic occludin-occludin interactions. The C-terminal OCEL domain of ELL is also important for its function due to its interaction with other proteins [1,2,3,4].

The OCEL domain adopts an arch-shaped fold comprising three helices that form two separate anti-parallel coiled-coils and a loop that packs tightly against one of the coiled-coils (see <PDB:1XAW>) [1,3,4].

The profile we developed covers the entire OCEL domain.

Last update:

July 2021 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

OCEL, PS51980; Occludin/ELL (OCEL) domain profile  (MATRIX)


1AuthorsLi Y. Fanning A.S. Anderson J.M. Lavie A.
TitleStructure of the conserved cytoplasmic C-terminal domain of occludin: identification of the ZO-1 binding surface.
SourceJ. Mol. Biol. 352:151-164(2005).
PubMed ID16081103

2AuthorsBuschmann M.M. Shen L. Rajapakse H. Raleigh D.R. Wang Y. Wang Y. Lingaraju A. Zha J. Abbott E. McAuley E.M. Breskin L.A. Wu L. Anderson K. Turner J.R. Weber C.R.
TitleOccludin OCEL-domain interactions are required for maintenance and regulation of the tight junction barrier to macromolecular flux.
SourceMol. Biol. Cell. 24:3056-3068(2013).

3AuthorsSchuetz A. Radusheva V. Krug S.M. Heinemann U.
TitleCrystal structure of the tricellulin C-terminal coiled-coil domain reveals a unique mode of dimerization.
SourceAnn. N. Y. Acad. Sci. 1405:147-159(2017).
PubMed ID23924897

4AuthorsQi S. Li Z. Schulze-Gahmen U. Stjepanovic G. Zhou Q. Hurley J.H.
TitleStructural basis for ELL2 and AFF4 activation of HIV-1 proviral transcription.
SourceNat. Commun. 8:14076-14076(2017).
PubMed ID28134250

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