Poly(A) tail length and PABP-dependent inhibition of translation by hnRNP-Q2 in Krebs extract.

<p>(A) Krebs extract that was not nuclease-treated was programmed with Cap-Luc mRNAs (0.2 µg/ml) bearing poly(A) tails of the indicated length. Control buffer of hnRNP-Q2 (20 µg/ml) was added to the reaction mixtures as indicated. (B) Sequestering of PABP by Paip2 renders translation insensitive to the poly(A) tail length and inhibition by hnRNP-Q2. Cap-Luc mRNA with increasing poly(A) tails was translated in the untreated extract in the presence of Paip2 (15 µg/ml) as described for panel A. hnRNP-Q2 (20 µg/ml) was added to the reaction mixtures where indicated. Inhibition of translation by hnRNP-Q2 is shown on the top of the panels. (C) Endogenous [³⁵S]methionine incorporation in the untreated extract in the presence of the indicated concentrations of hnRNP-Q2 or 10 µM hippuristanol (Hipp). Incubation was at 32°C for 2 h. Average values for trichloroacetic acid-insoluble radioactivity in 1-µl aliquots of the samples from three assays with standard deviations are shown.