Figure 4.

Cleavage of β-catenin, but not plakoglobin, impairs association with α-catenin. α-Catenin, β-catenin, and plakoglobin were immunoprecipitated from 250 μg of lysates prepared from control (C), viable (V), or apoptotic (A) HUVEC, and analyzed by SDS-PAGE and Western blotting. In panel a, samples immunoprecipitated with the anti-α-catenin antibody were analyzed by use of the anti-β-catenin (^571–781 C) or plakoglobin antibodies. Direct lysates (D) of apoptotic cells are shown for comparison. Fragments B and C, but not D, of β-catenin can still associate with α-catenin, whereas all apoptotic fragments of plakoglobin retain their ability to bind to α-catenin. (b) Samples immunoprecipitated with antibody ^571–781 C to β-catenin or anti-plakoglobin antibodies were analyzed by Western blot with anti-α-catenin or anti-β-catenin (^571–781 C) antibody. In apoptotic cells, β-catenin, but not plakoglobin, displays reduced binding of α-catenin, even though all of the fragments of β-catenin are immunoprecipitated.