Probable ATP-dependent RNA helicase. During immune response, may enhance IFNB1 expression via IRF3/IRF7 pathway (By similarity). ATP + H2O = ADP + H(+) + phosphate Shuttles between the nucleus and the cytoplasm in an XPO1-dependent manner. Widely expressed at the mRNA level, with highest levels in testis (PubMed:9381176). Testis-specific (at protein level). Expressed predominantly in spermatogonia, but occasionally detected in some pre-leptotene/leptotene spermatocytes (PubMed:15294876). Located in the 'azoospermia factor a' (AZFa) region on chromosome Y which is deleted in Sertoli cell-only syndrome. This is an infertility disorder in which no germ cells are visible in seminiferous tubules leading to azoospermia. Belongs to the DEAD box helicase family. DDX3/DED1 subfamily.