FIGURE 7.

Inhibition of ss-HRP secretion by Gallein and GRK2ct. HeLa cells were transfected with ss-HRP expression vector for 24 h before washing cells and then incubating another 5 h before assaying secreted HRP activity in the media. In addition, cells were transfected 24 h before the ss-HRP transfection with empty vector pcDNA3 (as control), GRK2ct, GRK2ctR587Q, Golgi-GRK2ct, or Golgi-GRK2ctR587Q, as indicated, or cells were treated with 10 μm gallein and fluorescein for a total of 5.5 h before measuring secreted HRP activity as described under “Experimental Procedures.” Bars represent the mean ± S.D. of HRP activity in the medium from three experiments each performed in triplicate. Statistical significance compared with control (pcDNA3) was tested using unpaired t test (*, p < 0.001). The lower panel shows a Western blot using cell lysates and an anti-GRK2 antibody to demonstrate similar expression levels of GRK2ct, GRK2ctR587Q, Golgi-GRK2ct, and Golgi-GRK2ctR587Q.