Multifunctional RNA-binding protein involved in the regulation of pre-mRNA splicing, mRNA stability and mRNA translation important for cell fate decision and differentiation. Plays a major role in pre-mRNA alternative splicing regulation. Mediates preferentially muscle-specific exon inclusion in numerous mRNAs important for striated cardiac and skeletal muscle cell differentiation. 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. 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. Plays a role in the regulation of mRNA stability and mRNA translation to which it is bound. Involved in myogenic differentiation by regulating myog levels (PubMed:20338237). Binds to a huge amount of mRNAs. Required for embryonic heart development, sarcomer and M-band formation in striated muscles (PubMed:20338237). Expressed both maternally and zygotically (PubMed:10842088). Zygotic transcription is initiated in the early gastrula embryo in paraxial mesoderm that is fated to give rise to somites (PubMed:10842088). During the course of gastrulation and neurulation, it is expressed in somitic paraxial mesoderm is centered within the myoD expression domain (PubMed:10842088). Expressed in developing somites at larval stages (PubMed:25217815). As development proceeds it is also expressed in the cardiac primordium and the lens vesicle (PubMed:10842088, PubMed:25217815). Expressed in hypaxial migrating cells and branchiomeric cranial muscles (PubMed:25217815). In the heart expression is confined to the myocardium (PubMed:10842088). Up-regulated by the myogenic factor myoD during gastrulation. The RRM domain is necessary for mRNA stability and mRNA translation regulation.