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