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The 26S proteasome is the chief site of regulatory protein turnover in eukaryotic cells. It comprises one 20S catalytic complex (composed of four stacked rings of seven members) and two axially positioned 19S regulatory complexes (each containing about 18 subunits) that control substrate access to the catalytic chamber. In most cases, targeting to the 26S(More)
The interferon (IFN) system is a major effector of the innate immunity that allows time for the subsequent establishment of an adaptive immune response against a wide-range of pathogens. Their diverse biological actions are thought to be mediated by the products of specific but usually overlapping sets of cellular genes induced in the target cells.(More)
RNA helicase-like receptors MDA-5 but not RIG-I has been shown to be essential for triggering innate immune responses against picornaviruses. However, virus-host co-evolution has selected for viruses capable of replicating despite host cells antiviral defences. In this report, we demonstrate that RIG-I is degraded during encephalomyocarditis virus (EMCV)(More)
Interaction of protein synthesis initiation factors with mRNA has been studied in order to characterize early events in the eukaryotic translation pathway. Individual reovirus mRNAs labeled with 32P in the alpha position relative to the m7G cap and eukaryotic initiation factor (eIF)-4A, -4B, and -4F purified from rabbit reticulocytes were employed. It was(More)
Three mammalian eukaryotic initiation factors (eIF) are required for the ATP-dependent binding of mRNA to the 40 S ribosomal subunit. These three factors, eIF-4A, eIF-4B, and eIF-4F, have also been isolated from wheat germ. Three assays were used to measure the ability of the wheat germ factors to interact with and/or substitute for the mammalian factors.(More)
The hepatitis A virus 3C protease and 3D RNA polymerase are present in low concentrations in infected cells. The 3C protease was previously shown to be rapidly degraded by the ubiquitin/26S proteasome system and we present evidence here that the 3D polymerase is also subject to ubiquitination-mediated proteolysis. Our results show that the sequence(More)
The amino acid sequence LLVRGRTLVV, which is probably located in a strand-turn-strand structure, has been identified as a protein destruction signal in the rapidly degraded encephalomyocarditis virus 3C protease. Mutations within this sequence reduced the susceptibility of the 3C protease toward ubiquitination and degradation in rabbit reticulocyte lysate.(More)
The interaction of three protein synthesis initiation factors, eukaryotic initiation factor (eIF)-4A, -4B, and -4F, with mRNA has been examined. Three assays specifically designed to evaluate this interaction are RNA-dependent ATP hydrolysis, retention of mRNAs on nitrocellulose filters, and cross-linking to periodate-oxidized mRNAs. The ATPase activity of(More)
The picornavirus 3C proteases are required for the processing of viral polyproteins during infections of host cells. Here we report that the 3C protease of the hepatitis A virus, like that of the encephalomyocarditis virus, is a substrate for rapid, ubiquitin-mediated degradation in vitro. Ubiquitin was shown to stimulate the turnover of the hepatitis virus(More)