Figure 4.

Expression and activity of the MLCK-GFP fusion proteins. (A) Whole cell lysates of HeLa cells expressing the long, short, and truncated MLCK-GFP fusions are shown. Lanes: 1, avian long MLCK; 2, avian short MLCK; 3, avian NH₂-terminal extension; 4, avian NH₂-terminal extension containing all five DXRXXL motifs; and 5, avian short MLCK containing all five DXRXXL motifs. (B) MLCK-GFP fusions were immunoprecipitated with a GFP pAb from untransfected, or long MLCK-GFP and short MLCK-GFP transfected, HeLa cells. Both the long and short MLCK-GFPs phosphorylated the RLC in a Ca²⁺/calmodulin-dependent manner.