RNA-binding protein that plays a central role in myelinization. Binds to the 5'-NACUAAY-N(1,20)-UAAY-3' RNA core sequence. Acts by regulating pre-mRNA splicing, mRNA export, mRNA stability and protein translation. Required to protect and promote stability of mRNAs which promotes oligodendrocyte differentiation. Participates in mRNA transport by regulating the nuclear export of MBP mRNA. Also involved in regulation of mRNA splicing of some pre-mRNA. Acts as a translational repressor (By similarity). Essential for notochord development. Homodimer. Does not require RNA to homodimerize. First detected in the chordamesoderm of the dorsal blastopore lip of the mid-gastrula embryo (stage 11). This tissue, which differentiates into the notochord. In late gastrula embryos (stage 13), it is highly expressed in the notochord, and the original expression domain expands to include the tissue surrounding the blastopore. In neurula embryos, it is maintained in the notochord and the circumblastoporal region and now also extends to the paraxial mesoderm and the neuroectoderm. By the tailbud stage, it is expressed in various mesodermal and neural tissues. Highly expressed in the brain and the neural tube. Maintained throughout development to the tadpole stage (stage 35).