Crystallography of liver alcohol dehydrogenase complexed with substrates.

The cytoplasmic metabolism of two adenovirus (Ad2)-specific messenger RNAs, encoded within the left-hand 11% of the Ad2 genome, has been examined in a transformed rat embryo line (strain 8617). Both the accumulation of labeled mRNA and the decay of pulse-labeled mRNA after an actinomycin D chase indicate a stochastic turnover of these Ad2-specific mRNA with half lives of approximately 35 and 100 minutes, considerably shorter than the half-life of the bulk of mRNA.The separation of mRNA molecules according to the length of poly(A) showed that the poly(A) of the Ad2-specific mRNAs was shortened both during continuous and pulse-chase labeling. Moreover, consistent with the observed rates of mRNA turnover, the rate of poly(A) shortening in the Ad2 mRNAs was found to be faster than that of the bulk mRNA population. In addition, the results suggested that both mRNA turnover and poly(A) shortening proceeded by random endonucleolytic cleavage.