RNA-binding protein involved in deadenylation-dependent decapping of mRNAs, leading to the degradation of mRNAs (PubMed:17936923, PubMed:20543818, PubMed:20584987, PubMed:20852261). Acts as a scaffold protein that connects deadenylation and decapping machinery (PubMed:17936923, PubMed:20543818, PubMed:20584987, PubMed:20852261). Required for cytoplasmic mRNA processing body (P-body) assembly (PubMed:17936923, PubMed:20543818, PubMed:20584987, PubMed:20852261). (Microbial infection) In case of infection, required for translation and replication of hepatitis C virus (HCV). Interacts (via region A) with DDX6/RCK (PubMed:20543818, PubMed:20584987, PubMed:31422817, PubMed:31439631). Interacts (via region H and region C) with LSM1 and LSM4 (PubMed:20584987, PubMed:20852261). Interacts (via region N) with DCP1A, DCP2, EDC3, EDC4 and XRN1 (PubMed:20584987, PubMed:20543818). Interacts with the CCR4-NOT complex (PubMed:20584987). Interacts with the Lsm-containing SMN-Sm protein complex (PubMed:20543818). Interacts with EIF4ENIF1/4E-T (PubMed:26027925, PubMed:32354837). Predominantly cytoplasmic (PubMed:22090346). Shuttles between the nucleus and the cytoplasm in a CRM1-dependent manner (PubMed:22090346). Enriched in splicing speckles. Localization to nuclear foci and speckles requires active transcription. Excluded from the nucleolus (PubMed:22090346). Ubiquitous. The region A, also named N-term, mediates the interaction with DDX6/RCK and is required for cytoplasmic mRNA processing body assembly. The region C, also named Pat-C, is required for RNA-binding and mediates the binding with the Lsm-containing SMN-Sm protein complex and the decapping machinery. It folds into an alpha-alpha superhelix, exposing conserved and basic residues on one side of the domain. Belongs to the PAT1 family. Extended N-terminus.