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 (By similarity). . This is the function of CSDC2 (cold shock domain containing C2, Ensembl gene identifier ENSG00000172346).