Research Paper Volume 10, Issue 3 pp 402—424

Preferential Ty1 retromobility in mother cells and nonquiescent stationary phase cells is associated with increased concentrations of total Gag or processed Gag and is inhibited by exposure to a high concentration of calcium

Figure 6. Calcium treatment reduces Gag levels and masks or suppresses the effects of brp1∆ or lsm1∆ mutations. (A) Western blot of protein extracts from cells grown to exponential phase in YPD with or without 100 mM calcium chloride probed with an affinity-purified polyclonal Gag antibody (upper panel). Arrows indicate the migration of the different forms of Gag, and the number on the left indicates the migration of a protein size standard in kilodaltons (kD). Note that the blot was moderately overexposed to better show the weak signal for calcium-treated cells. The lower panel shows the same blot stripped and reprobed with a beta-actin antibody as a loading control. The extract from an spt3∆ mutant was used as a control for low expression. (B) His+ frequencies for mid-exponential phase cells of the indicated genotypes grown in YPD medium without (Mock) or with 100 mM calcium chloride (Ca). Data are for three trials. Horizontal bars indicate comparisons between treated and untreated cells. (C) Same as for panel B for three trials with a different set of mutant strains. Note that a log scale is used for the y-axis because of the large differences in frequencies. (D) Western blot for Gag in wild type (WT) and pmr1∆ mutant strains, as described for panel A. All data in graphs are mean values with standard deviation. Asterisks over individual columns indicate comparisons to wild type treated or untreated cells. Asterisks indicate significant differences as for Fig. 2.