B) Model for the role of the N-terminal domain and the NIM in the control of Sen1 action at ncRNAs. Nrd1 and Sen1 are likely independently recruited to the elongation complex. The recruitment of Nrd1 and Nab3 is mediated by the recognition of specific RNA sequences and enhanced by the interaction of Nrd1 CID with the S5P-CTD via the CID. Sen1 would be recruited either by unspecific binding to the nascent RNA or by possibly transient protein-protein interactions with RNAPII. The interaction of Sen1 NIM with Nrd1 CID also enhances Sen1 recruitment. The interaction of Sen1 Nter with the CTD could facilitate the loading of Sen1 to the nascent RNA in the vicinity of paused RNAPII. Sen1 would translocate along the nascent RNA to induce dissociation of the elongation complex. The release of Sen1 from Nrd1 would be required for the CID to be available to recruit TRAMP for subsequent processing/ degradation of the released RNA. 