Two distinct classes of NNS-dependent snoRNA transcription termination. (A) Pile-up analysis of a 900-bp region downstream from snoRNA genes for all NNS-terminated snoRNAs (left), snoRNAs with RRP6/DIS3-FRB PAT (xPAT) cluster peaks associated with downstream DRS (roadblocked snoRNAs; middle), and snoRNA xPAT cluster peaks without downstream DRS (nonroadblocked snoRNAs; right). (i,ii,iv) PATs for the indicated strains. (ii) Pol II ChIP signal from NRD1-FRB strains in the absence (purple) or presence (green) of rapamycin, with the gray line indicating the log₂ ratio of rapamycin treated over untreated cells. (iii) Pol II occupancy as assayed by PAR-CLIP of Rpb2p for the indicated strains. (iv) The distribution of xPATs relative to nucleosome occupancy. (iv, middle) DRS signal (dashed gray line) included. The y-axes for all plots represent normalized reads. (B) Pile-up analysis on the centers of mass of clusters greater than or equal to twofold up-regulated in RRP6-FRB relative to RRP6/SEN1-FRB and lacking downstream DRS for the indicated data sets. Pol II PAR-CLIP and nucleosome occupancy are depicted as in A. The number of clusters included in pile-up analyses is indicated in the upper right (n = 547).