Catalyzes the ATP-dependent unwinding of RNA duplexes with a single-stranded 3' RNA extension (PubMed:27871484, PubMed:29844170, PubMed:29906447). Central subunit of many protein complexes, namely TRAMP-like, nuclear exosome targeting (NEXT) and poly(A) tail exosome targeting (PAXT) (PubMed:27871484, PubMed:29844170, PubMed:21855801). NEXT functions as an RNA exosome cofactor that directs a subset of non-coding short-lived RNAs for exosomal degradation. NEXT is involved in surveillance and turnover of aberrant transcripts and non-coding RNAs (PubMed:27871484, PubMed:29844170). PAXT directs a subset of long and polyadenylated poly(A) RNAs for exosomal degradation. The RNA exosome is fundamental for the degradation of RNA in eukaryotic nuclei. Substrate targeting is facilitated by its cofactor ZCCHC8, which links to RNA-binding protein adapters (PubMed:27871484). Associated with the RNA exosome complex and involved in the 3'-processing of the 7S pre-RNA to the mature 5.8S rRNA (PubMed:17412707, PubMed:29107693). May be involved in pre-mRNA splicing. In the context of NEXT complex can also in vitro unwind DNA:RNA heteroduplexes with a 3' poly (A) RNA tracking strand (PubMed:29844170). Can promote unwinding and degradation of structured RNA substrates when associated with the nuclear exosome and its cofactors. Can displace a DNA strand while translocating on RNA to ultimately degrade the RNA within a DNA/RNA heteroduplex (PubMed:29906447). Plays a role in DNA damage response (PubMed:29902117). ATP + H2O = ADP + H(+) + phosphate Activated when MTREX is incorporated into NEXT complex an the nuclear RNA exosome complex. Component of a TRAMP-like complex, an ATP-dependent exosome regulatory complex consisting of a helicase (MTREX), an oligadenylate polymerase (TENT4B or TENT4A), and a substrate specific RNA-binding factor (ZCCHC7 or ZCCHC8). Several TRAMP-like complexes exist with specific compositions and are associated with nuclear, or nucleolar RNA exosomes (PubMed:21855801). Identified in the spliceosome C complex. Component of the poly(A) tail exosome targeting (PAXT) complex made of PABPN1, ZFC3H1 and MTREX that directs a subset of long and polyadenylated poly(A) RNAs for exosomal degradation (PubMed:27871484). Component of the nuclear exosome targeting (NEXT) complex composed of MTREX, ZCCHC8, and RBM7 that directs a subset of non-coding short-lived RNAs for exosomal degradation (PubMed:27905398, PubMed:27871484). Interacts with ZCCHC8; this interaction bridges the interaction between RBM7 and MTREX (PubMed:27905398, PubMed:16263084, PubMed:29844170, PubMed:31358741). Binds to ZFC3H1 and RBM7 in a RNase-insensitive manner (PubMed:27871484). Interacts with EXOSC10; the interaction mediates the association of MTREX with nuclear RNA exosomes (PubMed:26166824). Interacts with isoform 1 of NVL in an ATP-dependent manner; the interaction is required to associate NVL with nuclear RNA exosome (PubMed:16782053, PubMed:26166824, PubMed:11991638, PubMed:16263084, PubMed:21855801, PubMed:27871484, PubMed:27905398, PubMed:31358741). Interacts with WDR74; the interaction dissociation in a late stage of rRNA synthesis is required for appropriate maturation of pre-60S particles and depends on the ATPase activity of NVL (PubMed:26456651, PubMed:29107693). Interacts with MPHOSPH6 (PubMed:17412707). Interacts with the RNA cap-binding complex proteins NCBP1 and SRRT (PubMed:30842217). Interacts with NRDE2; the interaction is direct and negatively regulates MTREX function in exosomal degradation by changing its conformation precluding interaction with ZFC3H1, the RNA cap-binding complex proteins NCBP1 and SRRT, and association with the exosome (PubMed:30842217, PubMed:30538148, PubMed:29902117). Interacts with the nuclear RNA exosome complex (PubMed:29906447). Belongs to the helicase family. SKI2 subfamily. Extended N-terminus. Extended N-terminus.