Scaffolding protein that specifically recognizes and binds dimethylarginine-containing proteins. In nucleus, acts as a coactivator: recognizes and binds asymmetric dimethylation on the core histone tails associated with transcriptional activation (H3R17me2a and H4R3me2a) and recruits proteins at these arginine-methylated loci. In cytoplasm, may play a role in the assembly and/or disassembly of mRNA stress granules and in the regulation of translation of target mRNAs by binding Arg/Gly-rich motifs (GAR) in dimethylarginine-containing proteins (By similarity). Component of mRNA stress granules. Interacts with FMR1, FXR1, FXR2, EWSR1, FUS, SERBP1, EEF1A1 and DDX3X or DDX3Y, and with the small nuclear ribonucleoprotein-associated proteins SNRPB and SNRPN. Interacts with 'Lys-48'-linked tetra-ubiquitin, but not with monoubiquitin or 'Lys-63'-linked ubiquitin chains. May interact with the exon junction complex (EJC) composed at least of CASC3, EIF4A3, MAGOH and RBM8A. Interacts with POLR2A (via the C-terminal domain (CTD)). Predominantly cytoplasmic. Associated with actively translating polyribosomes and with mRNA stress granules (By similarity). The Tudor domain specifically recognizes and binds asymmetric dimethylation of histone H3 'Arg-17' (H3R17me2a) and histones H4 'Arg-3', 2 tags for epigenetic transcriptional activation.