Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.25 (triphosphatase)
 1,529 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently it has been reported that a membrane fraction can be isolated from West Nile virus-infected BHK cells which contains the viral nonstructural (NS) proteins as major constituents (Wengler et al., 1990). In this report we show that treatment of these membranes with subtilisin releases the carboxy-terminal segment of the NS 3 protein as a soluble protein of about 50 kDa apparent molecular weight. This molecule, which is called the p50-S protein, can be purified by standard chromatographic procedures. The p50-S protein binds to poly(A) and apparently represents a nucleoside triphosphatase which is stimulated in the presence of ssRNA molecules. The data represent experimental support for the predicted role of this segment of the NS 3 protein as an RNA helicase. Some properties of the p50-S protein are described and a possible function of this protein segment during RNA synthesis is discussed.
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PMID:The carboxy-terminal part of the NS 3 protein of the West Nile flavivirus can be isolated as a soluble protein after proteolytic cleavage and represents an RNA-stimulated NTPase. 171 26

The genome of flaviviruses consists of an infectious single-stranded RNA molecule which contains a type 1 cap structure at the 5'-terminus. The cap is synthesized by RNA triphosphatase, guanylyltransferase and methyltransferase. Since flaviviruses replicate in the cytoplasm, it can be assumed that these functions are performed by virus-coded proteins. We previously showed that subtilisin treatment of membranes isolated from cells infected with the West Nile flavivirus results in release of a 50 kDa molecular weight fragment of the viral nonstructural protein NS 3. This so-called p50-S protein contains the residue gly (168) of NS 3 at the amino-terminus and represents an RNA-stimulated NTPase. In the present report we present experimental evidence which indicates that the p50-S protein also contains the active site of an RNA triphosphatase. The activity specifically cleaves the beta,gamma-triphosphate bond at the 5'-terminus of RNA. The localization of NS 3 protein sequence elements with known functions indicates that this multifunctional protein contains a protease in the amino-terminal part, a helicase in the central region and the RNA triphosphatase in the carboxy-terminal domain. An amino acid sequence element which may be involved in recognition of the 5'-terminal RNA triphosphate is tentatively identified. A homologous element may be present in the vaccinia virus-coded RNA triphosphatase.
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PMID:The NS 3 nonstructural protein of flaviviruses contains an RNA triphosphatase activity. 821 62