Multifunctional polyribosome-associated RNA-binding protein that plays a central role in neuronal development and synaptic plasticity through the regulation of alternative mRNA splicing, mRNA stability, mRNA dendritic transport and postsynaptic local protein synthesis of a subset of mRNAs (By similarity). Binds poly(G) and poly(U), and to a lower extent poly(A) and poly(C). Homodimer. Heterodimer. During early to late tailbud stage, expression intensifies in the craniofacial region with prominent staining in the endodermal, mesodermal and mesenchymal regions of the pharyngeal arches. By early tadpole stage (stage 35), expressed in the forebrain, midbrain, hindbrain and notochord in addition to craniofacial regions including the ear vesicles and eye. In the central nervous system (CNS) of late tadpoles (stage 45), expressed in the olfactory bulbs and the cerebellum. In adults, expressed predominantly in the brain. Expressed both maternally and zygotically. Zygotic expression begins just prior to gastrulation (stage 10) and gradually increases during subsequent embryonic stages. Belongs to the FMR1 family.