RNA-binding factor involved in multiple aspects of cellular processes like alternative splicing of pre-mRNA and translation regulation. Modulates alternative 5'-splice site and exon selection. Acts as a muscle cell differentiation-promoting factor. Activates exon skipping of the PTB pre-mRNA during muscle cell differentiation. Antagonizes the activity of the splicing factor PTBP1 to modulate muscle cell-specific exon selection of alpha tropomyosin. Binds to intronic pyrimidine-rich sequence of the TPM1 and MAPT pre-mRNAs. Required for the translational activation of PER1 mRNA in response to circadian clock. Binds directly to the 3'-UTR of the PER1 mRNA. Exerts a suppressive activity on Cap-dependent translation via binding to CU-rich responsive elements within the 3'UTR of mRNAs, a process increased under stress conditions or during myocytes differentiation. Recruits EIF4A1 to stimulate IRES-dependent translation initiation in respons to cellular stress. Associates to internal ribosome entry segment (IRES) in target mRNA species under stress conditions. Plays a role for miRNA-guided RNA cleavage and translation suppression by promoting association of AGO2-containing miRNPs with their cognate target mRNAs. Associates with miRNAs during muscle cell differentiation. Binds preferentially to 5'-CGCGCG[GCA]-3' motif in vitro. Interacts with TNPO3; the interaction mediates nuclear import of the protein and is disrupted by nuclear Ran bound to GTP. Interacts with EIF4G1 and WT1. Interacts with EIF4A1; the interaction is modulated under stress-induced conditions. Interacts with AGO1. Interacts with AGO2; the interaction occurs under both cell proliferation and differentiation conditions and in an RNA- and phosphorylation-independent manner. Interacts with DDX5; the interaction occurs in an RNA-independent manner (By similarity). Undergoes continuous nucleocytoplasmic shuttling. Upon nuclear import colocalizes with SR proteins in nuclear speckles. Arsenite stress-induced phosphorylation increases its subcellular relocalization from the nucleus to the cytoplasm and to cytoplasmic stress granules (SG) via a p38 MAPK signaling pathway. Primarily localized in nucleus and nucleoli under cell growth conditions and accumulated in the cytoplasm and cytoplasm perinuclear granules upon muscle cell differentiation (By similarity). Expressed in the suprachiasmatic nucleus (SCN). Expressed in myocytes; expression gradually increases during muscle cell differentiation (at protein level). Expressed in the suprachiasmatic nucleus (SCN). Accumulates according to a circadian rhythm in the SCN. Phosphorylated. Phosphorylated in vitro on Ser-306 by SRPK1. Phosphorylation on Ser-306 is induced upon cell stress signaling, which alters its subcellular localization and may modulate its activity on IRES-mediated mRNA translation (By similarity). Phosphorylated. Phosphorylation on Ser-306 is induced upon cell muscle differentiation. May be due to an intron retention.