Isoform 2 may participate in the regulation of nucleoplasmic coilin protein interactions in neuronal and transformed cells. Isoform 3 can regulate global protein synthesis by altering nucleolar numbers. Interacts with EPHA8 (By similarity). Isoform 2 interacts with COIL. Isoform 3 interacts with DLG4. The synaptic localization requires DLG4 interaction. Translocation to the nucleus in response to stimulation of NMDA receptors (NMDARs) in a calcium-independent manner. Isoform 3 is brain specific and highly enriched in the postsynaptic densities (PSDs), especially in cortical, striatal and hippocampal PSDs. Nuclear translocation of isoform 3 requires an NMDAR-dependent proteolytic cleavage. A 35 kDa N-terminal form shuttles to the nucleus.