RNA-binding component of messenger ribonucleoprotein complexes (mRNPs), storage particles that mask maternal mRNAs from the translational apparatus during oocyte maturation. Acts as a repressor of mRNA translation. Probably involved in the storage of translationally inactive mRNAs in the cytoplasm in order to prevent their degradation. Component of a ribonucleoprotein (RNP) complex, at least composed of lsm14a/rap55a, ybx2/frgy2, ddx6/Xp54 and eif4enif1/4E-T. Also forms a complex with prmt1 independently of ybx2/frgy2. Interacts with ddx6/Xp54 but does not appear to directly bind ybx2/frgy2. Different translationally-repressed mRNP complexes probably exist that contain either lsm14a/rap55a or lsm14b/rap55b depending on the developmental stage (By similarity). Localizes to cytoplasmic particles in stage VI oocytes and eggs. The RGG repeats are required for interaction with ddx6/Xp54 and accumulation in ribonucleoprotein complexes. Phosphorylated. Belongs to the LSM14 family.