Figure 4.

Cell cycle progression is delayed after G₁ phase in rpn4Δ mutant. (A) A larger fraction of rpn4Δ cells have 2N DNA content in unsynchronized cultures. DNA flow cytometry was carried out with wild-type (RPN4) and rpn4Δ cells. The abscissa ordinate indicate, respectively, the number of cells and relative DNA content. (B and C) Cell cycle progression of rpn4Δ cells is delayed after G₁ phase. Wild-type and congenic rpn4Δ cells were synchronized in late G₁ by using α factor. Initial samples were taken after 2 h of G₁ arrest, and subsequent samples were taken at 20-min intervals after release from the arrest. The samples were analyzed by using DNA flow cytometry (B) and by determining the fraction of budded cells (C). Data shown in C are the means of triplicate measurements.