Three-layered control of mRNA poly(A) tail synthesis in Saccharomyces cerevisiae

In this study, Turtola et al. set out to study the exact requirements for polyadenosine (pA) tail length control. Using in vivo and in vitro approaches in budding yeast, the authors report a three-layered control of nuclear poly(A) tail synthesis, where one primary mechanism is backed up by two “fail-safe” mechanisms. Nuclear poly(A) binding protein Nab2p executes the primary control. When Nab2p is limiting, the nuclear pool of Pab1p, the second major PABP in yeast, controls the process. When both PABPs are absent, the cleavage and polyadenylation factor (CPF) limits pA tail synthesis.