CEACAM7 is a human cellular adhesion protein that is expressed on the surface of
colon and rectum epithelial cells and is downregulated in colorectal cancers. It
achieves cell adhesion through dimerization of the N-terminal IgV domain. The
crystal structure of the N-terminal dimerization domain of CEACAM has been
determined at 1.47 Å resolution. The overall fold of CEACAM7 is similar to
those of CEACAM1 and CEACAM5; however, there are differences, the most notable
of which is an insertion that causes the C'' strand to buckle, leading to the
creation of a hydrogen bond in the dimerization interface. The Kdimerization for
CEACAM7 determined by sedimentation equilibrium is tenfold tighter than that
measured for CEACAM5. These findings suggest that the dimerization affinities of
CEACAMs are modulated via sequence variation in the dimerization surface.
