RNA-binding protein that plays a central role in spermatogenesis. Required for meiotic entry and germline differentiation, at the transition between G2 and M phases of meiosis I. Acts by regulating translation of specific mRNAs, possibly by binding to their 3'-UTR. Essential for translation of twine (twe) mRNA. Required for the expression of various genes such as CG6784, CG17210, CG15841 scpr-B, scpr-C, and rho-6.