Figure 4

MPIase stimulates preprotein translocation. (a) pOmpA is accumulated on MPIase depletion. KS22 and KS23 cells were cultivated as described in the legend to Fig. 2d, except that IPTG induction was omitted. Cells were then pulse-labeled for 30 s, and then chased for the indicated periods. OmpA and pOmpA were immunoprecipitated, followed by SDS-PAGE/autoradiography. (b) The results in (a) were quantitated and plotted against chase time. (c) pOmpA is also accumulated on MPIase depletion in the presence of Tam41p. KS22 and KS23 cells harboring pTet-Tam41p were subjected to pulse-chase experiments as in (a). (d) The results in (c) were quantitated and plotted against chase time. (e) Summary of the pulse-chase experiments. The half-lives of pOmpA in (b,d) were calculated.