EIF4E-binding protein that regulates translation and stability of mRNAs in processing bodies (P-bodies) (PubMed:16157702, PubMed:24335285, PubMed:27342281, PubMed:32354837). Plays a key role in P-bodies to coordinate the storage of translationally inactive mRNAs in the cytoplasm and prevent their degradation (PubMed:24335285, PubMed:32354837). Acts as a binding platform for multiple RNA-binding proteins: promotes deadenylation of mRNAs via its interaction with the CCR4-NOT complex, and blocks decapping via interaction with eIF4E (EIF4E and EIF4E2), thereby protecting deadenylated and repressed mRNAs from degradation (PubMed:27342281, PubMed:32354837). Component of a multiprotein complex that sequesters and represses translation of proneurogenic factors during neurogenesis (By similarity). Promotes miRNA-mediated translational repression (PubMed:24335285, PubMed:27342281, PubMed:28487484). Required for the formation of P-bodies (PubMed:16157702, PubMed:22966201, PubMed:27342281, PubMed:32354837). Involved in mRNA translational repression mediated by the miRNA effector TNRC6B by protecting TNRC6B-targeted mRNAs from decapping and subsequent decay (PubMed:32354837). Also acts as a nucleoplasmic shuttling protein, which mediates the nuclear import of EIF4E and DDX6 by a piggy-back mechanism (PubMed:10856257, PubMed:28216671). Interacts (via YXXXXLphi motif) with EIF4E (PubMed:10856257, PubMed:16157702, PubMed:23991149, PubMed:24335285, PubMed:25923732, PubMed:28487484). Interacts (via YXXXXLphi motif) with EIF4E2 (PubMed:23991149, PubMed:28487484). Interacts with DDX6 (PubMed:26027925, PubMed:27342281, PubMed:28216671, PubMed:31422817, PubMed:32354837, PubMed:26489469, PubMed:31439631). Interacts with CSDE1/UNR (PubMed:27342281, PubMed:32354837). Interacts with CNOT1; promoting association with the CCR4-NOT complex (PubMed:26027925, PubMed:27342281, PubMed:32354837, PubMed:26489469). Interacts with LSM14A; promoting EIF4ENIF1 localization to P-bodies (PubMed:26027925, PubMed:32354837, PubMed:29510985). Interacts with PATL1 (PubMed:26027925, PubMed:32354837). Interacts with importin beta only in the presence of importin alpha, suggesting a direct interaction with importin alpha (PubMed:10856257). Interacts with APOBEC3G in an RNA-dependent manner (PubMed:16699599). Predominantly cytoplasmic (PubMed:10856257). Mainly localizes to processing bodies (P-bodies) (PubMed:16157702). Shuttles between the nucleus and the cytoplasm in a CRM1-dependent manner (PubMed:10856257). Localization to nuclear foci and speckles requires active transcription (PubMed:22090346). Widely expressed. Intrinsically disordered protein with multiple low-complexity regions that confer binding to multiple RNA translation, deadenylation and decapping factors. The YXXXXLphi motif mediates interaction with eIF4E (EIF4E and EIF4E2). Phosphorylation by MAPK8/JNK1 and or MAPK9/JNK2 in response to oxidative stress promotes P-body assembly (PubMed:22966201). Phosphorylated during meiotic maturation (By similarity). Belongs to the 4E-T/EIF4E-T family.