2'-5'-oligoadenylate synthetase 3 (OAS3)

2'-5'-Oligoadenylate synthetase 3 (OAS3) is an interferon-stimulated enzyme central to innate antiviral immunity. It contains three tandem OAS domains but only the third (C-terminal) domain is catalytically active. Upon binding long double-stranded RNA (dsRNA), as produced during viral infection, OAS3 synthesizes 2’-5’ linked oligoadenylates (2-5As) from ATP. These 2-5As function as second messengers, activating the latent endoribonuclease RNase L. Activated RNase L degrades viral and cellular RNA, inhibiting viral replication and triggering apoptotic or stress pathways in infected cells. OAS3 is more sensitive to dsRNA than other OAS family members and preferentially produces oligoadenylates of sufficient length to robustly activate RNase L. OAS3 thus serves as both a sensor of cytosolic dsRNA and as a regulator of downstream antiviral responses, playing a critical role in interferon-induced cellular defenses[1][2][3].

Other names

2'-5'-oligoadenylate synthase 32-5A synthase 3p100 OASp100P/OKcl.4(2-5')oligo(A) synthase 32'-5'oligoadenylate synthetase p1002-5A synthetase 3100kDaoligoadenylate synthetase 3

Induction of 2'-5'-oligoadenylate synthesis upon dsRNA binding, leading to RNase L pathway activation and cellular/viral RNA degradation