RNA14 AND RNA15 PROTEINS AS COMPONENTS OF A YEAST PRE-MESSENGER-RNA 3'-END PROCESSING FACTOR

Most eukaryotic pre-messenger RNAs are processed at their 3' ends by e ndonucleolytic cleavage and polyadenylation. In yeast, this processing requires polyadenylate [poly(A)] polymerase (PAP) and other proteins that have not yet been characterized. Here, mutations in the PAP1 gene were shown to be synergistically lethal with previously identified mu tations in the RNA14 and RNA15 genes, which suggests that their encode d proteins participate in 3'-end processing. Indeed, extracts from ma1 4 and ma15 mutants were shown to be deficient in both steps of process ing. Biochemical complementation experiments and reconstitution of bot h activities with partially purified cleavage factor I (CF I) validate d the genetic prediction.