Fig. 6.
Intracellular localization of 220- and 130-kDa MLCKs in REF-52 cells. REF-52 cells transiently expressing either green fluorescent protein (GFP)-220-kDa MLCK or Fl-130-kDa MLCK were fixed, and MLCKs were detected by direct visualization of GFP or by staining cells with a mouse anti-Flag antibody and Alexa 488-conjugated goat-anti-mouse secondary antibody. Each vertical row represents the same cell expressing 220 (A–C)- or 130 (D–F)-kDa MLCK. GFP or Alexa 488 images are shown in A and D; the actin is visualized with rhodamine phalloidin in B and E. Merged images are shown in C and F (MLCK in green, C; F-actin in red, F). The 220-kDa MLCK colocalizes with thick actin stress fibers and is excluded from the peripheral tips of the filaments. The 130-kDa MLCK is concentrated in the perinuclear region and periphery of the cell and does not colocalize with F-actin.