Sequence-specific RNA-binding protein which acts as a translational repressor in the basal unstimulated state but, following neuronal stimulation, acts as a translational activator. In contrast to CPEB1, does not bind to the cytoplasmic polyadenylation element (CPE), a uridine-rich sequence element within the mRNA 3'-UTR, but binds to a U-rich loop within a stem-loop structure. Required for the consolidation and maintenance of hippocampal-based long term memory. In the basal state, binds to the mRNA 3'-UTR of the glutamate receptors GRIA2/GLUR2 mRNA and negatively regulates their translation. Also represses the translation of DLG4, GRIN1, GRIN2A and GRIN2B. When activated, acts as a translational activator of GRIA1 and GRIA2. In the basal state, suppresses SUMO2 translation but activates it following neuronal stimulation. Binds to the 3'-UTR of TRPV1 mRNA and represses TRPV1 translation which is required to maintain normal thermoception. Binds actin mRNA, leading to actin translational repression in the basal