5'-O-Monophosphoryladenylyl(2' goes to 5')adenylyl(2' goes to 5')adenosine is an antagonist of the action of 5'-O-triphosphoryladenylyl-(2' goes to 5')adenylyl(2' goes to 5')adenosine and double-stranded RNA.

5'-O-Monophosphoryladenylyl(2' goes to 5')adenylyl-(2' goes to 5')adenosine [(2' goes to 5')(pA)3] antagonizes the protein synthesis inhibitory effects of 5'-O-triphosphoryladenylyl-(2' goes to 5')adenylyl(2' goes to 5')adenosine by preventing activation of the (2' goes to 5')oligo(a)-activated ribonuclease which degrades mRNA. The oligoribonucleotide (2' goes to 5')(pA)3 also antagonizes the translational inhibitory capacity of poly(I).poly(C) in extracts of interferon-treated L cells, suggesting that (2' goes to 5')oligo(A) is the primary mediator of the protein synthesis inhibitory effects of poly(I).poly(C) in this cell-free system.