Does not have 2'-5'-OAS activity, but can bind double-stranded RNA. Expressed at highest level in brain with lesser amounts in spleen, kidney, stomach, liver, intestine, ovary, skin and testis. Not detected in lung, thymus, heart and uterus. Expressed in embryonic stem cells and embryonic fibroblasts (PubMed:11418248). Detected 1 week after birth in developing ovary (PubMed:27663720). By interferon (IFN) and polyinosinic:polycytidylic acid (poly I:C). Belongs to the 2-5A synthase family.