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 such as MBP and CDKN1B which promotes oligodendrocyte differentiation. Participates in mRNA transport by regulating the nuclear export of MBP mRNA. Also involved in regulation of mRNA splicing of MAG pre-mRNA. Acts as a translational repressor (By similarity). Homodimer. Does not require RNA to homodimerize. Able to heterodimerize with BICC1 (By similarity). The KH domain and the Qua2 region are involved in RNA binding. Methylated by PRMT1. Tyrosine phosphorylated at its C-terminus, probably by FYN. Phosphorylation leads to decreased mRNA-binding affinity, affecting transport and/or stabilization of MBP mRNA (By similarity).