. 2009 Sep;1(3):a003061. doi: 10.1101/cshperspect.a003061

Table 1.

Constitutive molecular components of the major types of symmetrical (homotypic) junctions

	Occurrence	Associated filaments	Transmembrane proteins and glycoproteins	Specific plaque proteins
DesmosomesMaculae adherentes	Epithelial cells, various types of cardiomyocytes, meningothelial cells, dendritic reticulum cells of the thymus and lymph follicles	Intermediate-sized filaments (keratins, vimentin, desmin)	Desmogleins 1–4^a desmocollins 1–3^a	Plakoglobin^b desmoplakin I/II plakophilins 1–3^a
Adherens junctionsZonulae adherentes Fasciae adherentes Puncta adhaerentia	Epithelial cells, endothelial cells, various types of cardiomyocytes, mesenchymal and neural cells	Microfilaments (actin)	Typical cadherins^a (e.g., E-cadherin, N-cadherin, P-cadherin, VE-cadherin, cadherin-11)	α- and β-Catenin, plakoglobin, protein p120, protein ARVCF, protein p0071, neurojungin (δ-catenin)^a, (plakophilin-2^c) proteins ZO-1, ZO-2, ZO-3
Tight junctionsZonulae occludentes Fasciae occludentes Puncta adhaerentia	Epithelial cells, endothelial cells	–^d	Occludin, claudins 1–24^a tricellulin(s)^e proteins of the JAMA-group, CAR^a, ESAM^a	Proteins ZO-1, ZO-2, ZO-3, cingulin
Gap junctions (nexus)	All kinds of tissue-forming cells	–	Connexins 1–21^a	Proteins ZO-1, ZO-2, ZO-3

Only established, i.e., repeatedly confirmed, constituent structural molecules are mentioned here; some further regulatory or peripherally associated molecules are not listed here but are discussed in the text.

^aOne or combinations of a few representatives, with cell type and cell layer specificities.

^bProteins of the so-called armadillo family are in italics.

^cOnly in specific proliferatively active cells (Rickelt et al. 2009).

^dActin microfilaments are seen near some tight junctions but their specific association is not clear.

^eThere are at least two mRNA splice products but only one protein has so far been localized.