CELLULAR-LOCALIZATION OF RNA14P AND RNA15P, 2 YEAST PROTEINS INVOLVEDIN MESSENGER-RNA STABILITY

RNA14 and RNA15 were originally identified by temperature-sensitive mu tations that cause a rapid decrease in poly(A)-tail length and overall mRNA levels at the restrictive temperature. We have raised antibodies to the RNA14 and RNA15 proteins, and used subcellular fractionation a nd immunofluorescence to localize these proteins within the yeast cell . RNA14p is a 73 kDa protein found in both the nucleus and the cytopla sm, whilst RNA15p is a 42 kDa protein detected only in the nucleus. Th e observation that both proteins are found in the nucleus is in agreem ent with previous genetic data which suggest am interaction between RN A14p and RNA15p. Also the joint nuclear localization is consistent wit h the biochemical data suggesting a role in polyadenylation. The detec tion of significant amounts of RNA14p in the cytoplasm opens the possi bility of a second function for this protein, either in cytoplasmic re gulation of mRNA deadenylation or, more interestingly, in mRNA stabili ty.