methods for generating high concentrations of CUTs. The Nrd1-Nab3-Sen1 and TRAMP pathway Transcription of CUTs is terminated by the Nrd1-Nab3-Sen1 complex. Collectively, Nrd1 and Nab3 are proteins which bind to specific sequences (GUAA/G and UCUUG respectively) of RNA and Sen1 is helicase. Nrd1-Nab3-Sen1 recruit the nuclear exosome which contains the degrading RRP6 subunit. Assisting in the Nrd1-Nab3-Sen1 pathway as a co-factor is the TRAMP complex, which is responsible for poly-adenylating transcripts and marking them for degradation. The TRAMP complex was discovered in Δrrp6 cells, when a certain population of poly-adenylated CUTs were attributed to the activity of a novel yeast polymerase, Trf4p. Trf4p was found to associate in a Trf4p/trf5p-Air1p/Air2p-Mtr4 complex (a collective complex referred to as TRAMP: Trf-Air-Mtr4 Polyadenylation complex) which serves as an alternative Poly(A) polymerase to Pap1p within S. Cerevisiae. Role of Xrn1 Cytoplasmic decay of unstable transcripts can also be attributed to the activity of decapping enzymes and Xrn1. Transcripts that enter the cytoplasm can be targeted by the Dcp1-Dcp2 complex which removes the 5' cap, allowing for the 5' to 3' exoribonuclease Xrn1 to degrade the transcript completely. The role of Dcp1-Dcp2 and Xrn1 in cytoplasmic decay has also been found to participate in the regulation of SUT levels. Relation with bidirectional promoters The transcription start sites of CUTs are located within nucleosome free, non-overlapping transcript pairs. These nucleosome free regions of the genome have been frequently correlated with the promoter regions of open reading frames and mRNA transcripts, indicating that a portion of CUTs are located within bidirectional promoters. Additionally, serial analysis of gene expression has demonstrated that the location of CUT 3' ends can be found in close proximity to the start features of ORFs in both sense and antisense configurations, indicating that the end of CUT sequences lay within the 5' promoter region of expressed proteins. Sense CUTs have been largely found in promoters associated with glucose catabolism genes, while antisense CUTs have no specific associations and are found dispersed in promoters across the entire genome. SUTs Stable uncharacterized transcripts or stable unannotated transcripts (SUTs) share certain similar characteristics to CUTs – they can originate from the intergenic region, are non-coding transcripts, and undergo 5' to 3' cytoplasmic degradation. Like CUTs, SUT transcription start sites are also found at nucleosome free regions and are associated with the promoters of protein coding genes. However, SUTs can be observed in both Δrrp6 mutants and