Required for male fertility and normal male germ cell differentiation (PubMed:32665638). Plays a role in spermatogenesis (PubMed:15649457). Binds to RNA but not to DNA (PubMed:15649457). Testis-specific. Detected in round spermatid cells from stage II-XI (at protein level). Expressed in germ cells from mid-pachytene spermatocytes to mid-round spermatids. Mice exhibit spermatozoa retention in stage IX tubules and a reduction in the number of sperm in the epididymis, leading to a reduction in fertility (PubMed:15649457). Show defects in germ-cell development (PubMed:32665638). Belongs to the ADAD family.