Involved in spermatogenesis and sperm function. Plays a role in regulation of cell growth. Binds to double-stranded DNA and RNA. Binds most efficiently to poly(I:C) RNA than to poly(dI:dC) DNA. Binds also to single-stranded poly(G) RNA. Binds non-specifically to the mRNA PRM1 3'-UTR and adenovirus VA RNA (By similarity). . This is the function of Ensembl gene identifier ENSG00000165209 (STRBP, spermatid perinuclear RNA binding protein).