Subunit of the trimeric poly(A) tail exosome targeting (PAXT) complex, a complex that 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 MTREX, which links to RNA-binding protein adapters. Component of the poly(A) tail exosome targeting (PAXT) complex made of accessory factors, such as PABPN1, ZFC3H1 and MTREX, and which directs a subset of long and polyadenylated poly(A) RNAs for exosomal degradation (PubMed:27871484). Co-localizes with component of the CBC-ARS2 (CBCA) complex. Binds to RNA exosome components. Interacts with NCBP1/CBP80, ZC3H18, MTREX and PABPN1 in a RNase-insensitive manner, and with PABPC4, PABPC1 and ZC3H14 in a RNase-sensitive manner (PubMed:27871484). Excluded from the nucleolus.