Leader cysteine autoprotease that cleaves itself from the nascent polyprotein during translation of the viral mRNA. Once released, plays a role in the inhibition of host innate immune response by interacting with host IRF3 and inducing its proteasomal degradation. Packages viral RNA to form a viral nucleocapsid and thereby protects viral RNA. Also plays a role in transcription regulation. Protects the incoming virus against IFN-induced effectors. Plays a role in viral entry. Interacts with host RPSA that acts as a cellular attachment receptor for the virus. Possesses also intrinsic ribonuclease (RNase) activity that can inhibit the production of type I interferon and assist in the development of persistent infections. Plays a role in cell attachment and subsequent fusion of viral and cellular membranes. Therefore, mediates together with envelope glycoprotein E2 the viral entry. Plays a role in cell attachment and subsequent fusion of viral and cellular membranes. Therefore, mediates together with envelope glycoprotein E1 the viral entry. Plays an essential role in the virus replication cycle by acting as a viroporin. Forms ion conductive pores, which alters the cell permeability allowing the transport of ions and other small molecules. Autoprotease that associates with the host chaperone JIV and cleaves the NS2-3 protein between NS2 and NS3. Also plays a role in the formation of infectious particles. Plays a role in the regulation of viral RNA replication. Multifunctional protein that contains an N-terminal protease and a C-terminal helicase, playing essential roles in viral polyprotein processing and viral genome replication. The chymotrypsin-like serine protease activity utilizes NS4A as an essential cofactor and catalyzes the cleavage of the polyprotein leading to the release of NS4A, NS4B, NS5A, and NS5B. Plays a role in the inhibition of host NF-kappa-B activation by interacting with and inhibiting host TRAF6. Interacts with NS5B to enhance RNA-dependent RNA polymerase activity. Acts as a cofactor for the NS3 protease activity. Induces a specific membrane alteration that serves as a scaffold for the virus replication complex (By similarity). Antagonizes host cell apoptosis by interacting with host ferritin heavy chain. The ORF4 protein physically binds host FTH1/FHC, resulting in the reduction of FTH1 protein levels in host cells. Reduction of FTH1 concentration further inhibits the accumulation of reactive oxygen in host cells, leading to reduced apoptosis. Regulates viral RNA replication by interacting with the 3'-untranslated region of viral RNA in a dose-dependent manner. At small concentrations promotes viral synthesis by interacting with the polymerase NS5B while at large concentrations, inhibits replication. Replicates the viral (+) and (-) genome. Leu is conserved at position P1 for all four cleavage sites. Alanine is found at position P1' of the NS4A-NS4B cleavage site, whereas serine is found at position P1' of the NS3-NS4A, NS4B-NS5A and NS5A-NS5B cleavage sites. a ribonucleoside 5'-triphosphate + RNA(n) = diphosphate + RNA(n+1) a ribonucleoside 5'-triphosphate + H2O = a ribonucleoside 5'-diphosphate + H(+) + phosphate ATP + H2O = ADP + H(+) + phosphate Interacts with host IRF3. Interacts with host OS9. Homodimer; disulfide-linked. Interacts with host RPSA. Homodimer; disulfide-linked (By similarity). Heterodimer with E1; disulfide-linked (By similarity). Homodimer; disulfide-linked (By similarity). Heterodimer with E1; disulfide-linked (By similarity). Interacts with host TRX2 (By similarity). Interacts with host TRAF6; this interaction inhibits host NF-kappa-B pathway. Interacts with NS5B; this interaction enhances RNA-dependent RNA polymerase activity. Interacts with protein NS4A. Interacts with host RAB5, this interaction facilitates the formation of NS4B-related complex. Interacts with host FTH1; this interaction plays a positive role in viral anti-apoptosis. Interacts with RNA-directed RNA polymerase. Interacts with host RSAD2; this interaction inhibits viral replication. Interacts with NS5A; this interaction promotes viral replication. The C-terminus membrane anchor of Erns represents an amphipathic helix embedded in plane into the membrane. Translated cap independently from an internal ribosome entry site (IRES). Heavily glycosylated. The viral RNA of pestiviruses is expressed as a single polyprotein which undergoes post-translational proteolytic processing resulting in the production of at least eleven individual proteins. The N-terminal protease cleaves itself from the nascent polyprotein autocatalytically and thereby generates the N-terminus of the adjacent viral capsid protein C. Cleavage between E2 and p7 is partial. Belongs to the pestivirus polyprotein family.