RNA-binding protein required for embryonic and postnatal development of muscle tissue. May regulate intracellular transport and local translation of certain mRNAs. Interacts with FMR1 and FXR2. Interacts with TDRD3, and with CYFIP2 but not with CYFIP1. Expressed in all tissues examined including heart, brain, kidney and testis. Belongs to the FMR1 family. 3 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.