Figure 3.
MKT1, PBP1 and LSM12 can all increase mRNA abundance. (A) Diagram (not to scale) of the CAT reporter mRNA, with or without 6 ‘boxB’ recognition sites in the 3′-UTRs, and fusion proteins with an N-terminal λ-N peptide and a C-terminal myc tag. (B) Expression of MKT1, PBP1 and LSM12 fusion proteins in both cell lines, with and without 1 day of tetracycline induction. Western blot with anti-myc, 5 × 106 cells per lane. C: control cells with no myc tag. Aldolase serves as a loading control. (C) Expression of CAT activity, and CAT RNA, in cells with or without inducible expression of λ-N-myc fusion proteins. RNA and protein extracts were prepared from cells with or without tetracycline treatment to induce fusion protein expression (100 ng/ml, 24 h). RNA was measured by northern blotting and CAT enzyme activity was assayed. Results are arithmetic mean ± standard deviation of at least three measurements. The increase for PBP1 without tetracycline addition is probably due to leaky expression (see (B)).