The End of the Message—Another Link Between Yeast and Mammals

Three reports in this week's issue ( p. 1511 , p. 1514 , and p. 1517 ) demonstrate that subunits of a protein factor that controls addition of the polyadenylated 3 ' tail to messenger RNA are conserved between yeast and mammals. In his Perspective, Manley describes what we know of the conservation of sequence signals for polyadenylation as well as of protein factors between yeast and mammals.