Multifunctional RNA-binding protein involved in the regulation of pre-mRNA splicing, mRNA stability and mRNA translation important for cell fate decision and differentiation (PubMed:20977548, PubMed:24375645, PubMed:29358667, PubMed:29104163). Plays a major role in pre-mRNA alternative splicing regulation (PubMed:26990106, PubMed:29104163). Mediates preferentially muscle-specific exon inclusion in numerous mRNAs important for striated cardiac and skeletal muscle cell differentiation (PubMed:29104163). Binds to intronic splicing enhancer (ISE) composed of stretches of GU-rich motifs localized in flanking intron of exon that will be included by alternative splicing (By similarity). Involved in embryonic stem cell (ESC) transition to cardiac cell differentiation by promoting pre-mRNA alternative splicing events of several pluripotency and/or differentiation genes (PubMed:26990106). Plays a role in the regulation of mRNA stability (PubMed:20977548, PubMed:24356969, PubMed:24375645, PubMed:29104163). Binds to 3'-untranslated region (UTR) AU-rich elements in target transcripts, such as CDKN1A and MYOG, leading to maintain their stabilities (PubMed:20977548, PubMed:24356969). Involved in myogenic differentiation by regulating MYOG levels (PubMed:20977548). Binds to multiple regions in the mRNA 3'-UTR of TP63 isoform 2, hence inducing its destabilization (PubMed:24375645). Promotes also the destabilization of the CHRM2 mRNA via its binding to a region in the coding sequence (PubMed:29104163). Plays a role in the regulation of mRNA translation (PubMed:29358667). Mediates repression of p53/TP53 mRNA translation through its binding to U-rich element in the 3'-UTR, hence preventing EIF4E from binding to p53/TP53 mRNA and translation initiation (PubMed:29358667). Binds to a huge amount of mRNAs (PubMed:29104163). Required for embryonic heart development, sarcomer and M-band formation in striated muscles (By similarity). Together with RBM20, promotes the expression of short isoforms of PDLIM5/ENH in cardiomyocytes (By similarity). (Microbial infection) Promotes hepatitis C virus (HCV) replication over translation through the inhibition of viral protein expression. Decreases viral translation by linking viral 5'- and 3'-UTRs, blocking 80S ribosome assembly on the viral IRES and enhancing the interaction of the mature core protein and 5'-UTR. Interacts with EIF4E; this interaction prevents EIF4E from binding to p53/TP53 mRNA and inhibits the assembly of translation initiation complex (PubMed:29358667). (Microbial infection) Interacts with HCV mature core protein; this interaction, which enhances the interaction of Core with 5'-UTR may favor viral replication over translation. (Microbial infection) Interacts with HCV Serine protease/helicase NS3. Expressed in fetal and adult heart and skeletal muscles (PubMed:22345307, PubMed:25313962). By p53/TP53 following DNA damage (at protein level) (PubMed:24356969). Up-regulated during embryonic stem cell (ESC) differentiation into cardiomyocytes (PubMed:19658189, PubMed:26990106). The RRM domain is necessary for mRNA stability and mRNA translation regulation (PubMed:24356969, PubMed:29358667). Unlikely isoform. Aberrant splice sites.