RNA-binding factor which binds specifically to the very 3'-UTR ends of both histone H1 and H3.3 mRNAs, encompassing the polyadenylation signal. Might play a central role in the negative regulation of histone variant synthesis in the developing brain. PIPPin-RNA complexes are located to the nucleus. Brain-specific. Expression restricted to the pyramidal neurons of the cerebral cortex and in the Purkinje cells of the cerebellum. At E18 dpc, expressed in the cerebellum.