Several properties of cadherin-4 and cadherin-5 were characterized by
using the cDNA transfection approach. The proteins of both cadherins h
ad a relative molecular mass of about 130 kDa and were present at the
cell periphery, especially at cell-cell contact sites. These cadherins
were easily digested with trypsin, and Ca2+ protected cadherin-4, but
not cadherin-5, from the digestion. In immunoprecipitation, cadherin-
4 co-precipitated with two major proteins of 105 kDa and 95 kDa, respe
ctively. The 105 kDa and the 95 kDa proteins are likely to correspond
to alpha- and beta-catenins. Cadherin-5 co-precipitated with only one
major protein of 95 kDa, but seems to associate with the 105 kDa prote
in. On the other hand, plakoglobin or gamma-catenin did not co-precipi
tate well with either cadherin-4 or cadherin-5 in immunoprecipitation,
but plakoglobin also appears to associate weakly with these cadherins
. Cadherin-4 transfectants aggregated within 30 minutes in a cell aggr
egation assay, but cadherin-5 transfectants did not aggregate under th
e same conditions. Furthermore, the transfectants of chimeric cadherin
-4 with cadherin-5 cytoplasmic domain showed cell aggregation activity
comparable to that of wildtype cadherin-4 transfectants, whereas the
transfectants of chimeric cadherin-5 with cadherin-4 cytoplasmic domai
n did not show appreciable cell aggregation, suggesting that the extra
cellular domains of cadherins, in conjunction with their cytoplasmic d
omains, play an important role in cell aggregation activity. These res
ults show that cadherin-4 is very similar to the classical cadherins,
whereas cadherin-5 is functionally as well as structurally distinct fr
om classical cadherins.