cadherins have a well conserved cytoplasmic domains.
Chordate classic cadherins have an extracellular
domain organization composed of five cadherin repeats.
Chordate classical cadherins can be further sub-divided
into type I and type II. Type I cadherins have a His-Arg-Val
sequence in the N-terminal cadherin repeat. Type II
cadherins are all chordate classical cadherins not in
classic cadherins have an extracellular domain organization
composed of at least two cadherin repeats. In contrast
to chordates, nonchordate classic cadherins have a variable
number of repeats in the extracellular domain (e.g.
HMR-1 in C. elegans has 2 repeats, and DN-cadherin in
Drosophila has 15 repeats). Also, they have additional
domains that are inserted between the cadherin repeats
and the transmembrane domain. These domains include
one or two Laminin A G domains, several cysteine-rich
repeats with similarity to the epidermal growth factor
cadherins are expressed in desmosomes and are essential
for desmosome formation. They contain 5 extracellular
cadherin repeats like chordate classical cadherins.
Tyrosine receptor kinase (RET) cadherins have a tyrosine
kinase domain in its cytoplasmic domain. The extracellular
domain contains one cadherin repeat.
cadherins have a very large extracellular domains
with many cadherin repeats (19 in CDH-3, 27 in Dachsous,
34 in Fat, hFat, and rFAT). As well, Fat, hFat, rFAT
and CDH-3 contain epidermal growth factor (EGF)-like
and Laminin AG-domain-like regions. These regions are
localized between the cadherin and transmembrane domains.
Fat-like cadherins may function in adhesion or signaling,
cadherins contain a seven-pass transmembrane receptor
which shows some similarity to the secretin family of
G-protein linked receptors. The large extracellular
domain of Flamingo contains nine cadherin repeats, two
globular laminin motifs, and four cystein-rich EGF motifs.
Also present is a subdomain located between the last
cadherin repeat and the first EGF domain which is highly
conserved across species. This region is known as the