FIG. 4.

Decreasing the abundance of an mRNA does not decrease its translational efficiency. (A) Total levels of URA3 and ACT1 mRNAs at various time points after addition of the tetracycline analogue doxycycline (2 μg/ml) to yeast cells grown in glycerol medium are shown. (B) Polysomal distribution of URA3 mRNA in yeast cells grown in glycerol medium in the presence (+) or absence (−) of doxycycline (doxy). The plasmid-derived URA mRNA was distinguished from the endogenous URA3 mRNA by using a probe complementary to a V5 six-His extension of the plasmid coding sequence (see Materials and Methods).