PKC-phosphorylated adducin was proteolyzed more quickly than unphosphorylated adducin.

Western blotting with (A) anti-adducin antibody and (B) anti-phosphoadducin antibody from a typical time course of μ-calpain proteolysis of recombinant alpha adducin. In lanes 1 to 4, adducin was phosphorylated by PKC before addition of calpain. In lanes 5 to 8, reaction mix included everything as in lanes 1 to 4 except PKC. (C) Quantitation of density of bands from 3 experiments measured with NIH Image and converted to relative optical density. The slope of the line for proteolysis of PKC-phosphorylated adducin is significantly different (P < .001) from the slope of the line for proteolysis of unphosphorylated adducin.