Does not have 2'-5'-olygoadenylate synthetase activity, but can bind double-stranded RNA (PubMed:15899864, PubMed:12396720). May play a role in the control of female fertility, possibly by binding to and inhibiting OAS1A (PubMed:15899864). Interacts with OAS1A, the interaction inhibits OAS1A catalytic activity. Expressed specifically in oocytes (at protein level) (PubMed:15899864). Expressed at highest level in ovary with lesser amounts in intestine, brain, thymus lung, kidney, liver and uterus (PubMed:17567914, PubMed:27663720). Detected in fully grown, germinal vesicle (GV)-intact oocytes and in oocytes at the metaphase II stage, with levels decreasing thereafter (at protein level) (PubMed:15899864). Detected 1 week after birth in developing ovary (PubMed:27663720). Detected at 17.5 dpc, with levels increasing thereafter (PubMed:17567914). Unlike other OAS1 proteins, not induced by polyinosinic:polycytidylic acid (poly I:C). Newborn mice are viable. Female mice display reduced fertility due to deficiencies in ovarian follicle development, reduced efficiency of ovulation, and the arrest of fertilized eggs at one-cell stage. Belongs to the 2-5A synthase family.