| Popis: |
Among the multiple proteins induced by interferon, the 2–5A synthetase has been shown to be involved in some of its antiviral actions. In the presence of dsRNA, this enzyme catalyzes the synthesis of 2′–5′ linked oligomers of adenosine,ppp(A′ 2p)nA Viral growth is inhibited through mRNA degradation mediated by a latent endoribonuclease which is activated by these 2–5A oliqomers. This effect is transient. The 2–5A oligomers are rapidily degraded by a 2′-phosphodiesterase (1). In addition to this antiviral role, the 2–5A system seems to be involved in the regulation of cell growth and differentiation (2,3). 2–5A activities associated with proteins of different sizes were detected in the cytoplasm and nucleoplasm (4, 5). Two functional mRNAs (1.6 and 1.8 kb in human cells (6, 7) and 1.8 and 3.6kb in mouse cells (5) were shown to encode 2–5A synthetase activity. The relationship between the different mRNAs, which seem to derive from the same gene by tissue specific differential splicing (6, 7) and the different proteins, as well as their cellular localization is still not clear. |
