Novel interactions at the essential N-terminus of poly(A) polymerase that could regulate poly(A) addition in Saccharomyces cerevisiae

► A yeast poly(A) polymerase lacking the first 18 amino acids is catalytically active. ► This mutant is non-functional when part of the mRNA 3′ end processing complex. ► Interaction with two essential processing complex subunits requires the N-terminal region. ► Additional regulatory interactions may be mediated by non-essential proteins.