Antiviral Protein

Zinc-finger anti-viral protein (ZAP) is a host antiviral factor that specifically inhibits the infection of cells by Moloney murine leukemia and multiple members of the alphavirus family, including Sindbis virus (SIN). An overexpression of ZAP prevents the accumulation of the viral RNA in the cytoplasm. The N terminus of ZAP contains four CCCH-type zinc-finger motifs. ZAP binds directly to specific viral RNA sequences through these zinc-finger motifs. The target sequence of ZAP in MLV was mapped to the 3′-LTR, and the target sequences in SIN were mapped to multiple fragments, but no obvious common motifs have been found in these sequences yet. Particularly, ZAP does not target ARE-containing mRNAs. Despite the lack of primary sequence homology, ZAP shares considerable similarities with tristetraproline (TTP). Both ZAP and TTP directly bind to their cognate target RNAs, and the zinc-finger motifs are required for the binding. ZAP directly interacts with the exosome, and it seems that...