Putative translation regulator. May be involved in the developmental translational regulation of maternal mRNAs. Possibly forms a heterodimer with p54 in the 6S and 15S mRNA-binding particles. Component of a ribonucleoprotein (RNP) complex, composed at least of elavl1/elrA and/or elavl2/elrB, igf2bp3/vg1RBP, ddx6/Xp54, ybx2/frgy2, lsm14b/rap55b and, in a subset of RNP complexes, stau1/staufen. Either free or associated with ribonucleoprotein particles. Expressed maternally. Expression peaks in the early stage II oocyte and levels are maintained throughout oogenesis. Phosphorylation activates in vitro RNA binding.