♦Genome polyprotein [Cleaved into: Core protein p21 (Capsid protein C) (p21)
♦ Core protein p19
♦ Envelope glycoprotein E1 (gp32) (gp35)
♦ Envelope glycoprotein E2 (NS1) (gp68) (gp70)] (Fragment)

NC_004102.1 ;  AF009606.1 

MSTNPKPQRKTKRNTNRRPQDVKFPGGGQIVGGVYLLTRRGPRLGVRATRKTSERSQPRGRRQPIPKARRPEGRAWAQPGYPWPLYGNEGLGWAGWLLSP
RGSRPSWGPTDPRRRSRNLGKVIDTLTCGFADLMGYIPLVGAPLGGASRALAHGVRVLEDGVNYATGNLPGCSFSIFLSALMSCLTTPASAYEVRNVSGI
YHVTNDCSNSSIAYEAAGMIMHTPGCVPCVRENNSSRCWVALTPTLAARNASVPTTTIRRHVDLLVGAATLCSAMYVGDLCGSVFLVSQLFTFSPRRYET
VQDCNCSIYPGHVSGHRMAWDMMMNWSPTAALVVSQLLRIPQAVVDMVAGAHWGVLAGLAYYSMVGNWAKVLIVMLLFAGVDGANTHTVGGTEGFATQRL
TSLFALGPSQKIQLINTNGSWHINRTALNCNDSFKTGFLAALFYVHKFNASGCPEHMASCRPIDKFDQGWGPVTYAEPSISEQRPYCWHYAPRPCGTIPA
SEVCGPVYCFTPSPVVVGTT

♦Core protein packages viral RNA to form a viral nucleocapsid, and promotes virion budding. Modulates viral translation initiation by interacting with HCV IRES and 40S ribosomal subunit. Also regulates many host cellular functions such as signaling pathways and apoptosis. Prevents the establishment of cellular antiviral state by blocking the interferon-alpha/beta (IFN-alpha/beta) and IFN-gamma signaling pathways and by inducing human STAT1 degradation. Thought to play a role in virus-mediated cell transformation leading to hepatocellular carcinomas. Interacts with, and activates STAT3 leading to cellular transformation. May repress the promoter of p53, and sequester CREB3 and SP110 isoform 3/Sp110b in the cytoplasm. Also represses cell cycle negative regulating factor CDKN1A, thereby interrupting an important check point of normal cell cycle regulation. Targets transcription factors involved in the regulation of inflammatory responses and in the immune response: suppresses NK-kappaB activation, and activates AP-1. Could mediate apoptotic pathways through association with TNF-type receptors TNFRSF1A and LTBR, although its effect on death receptor-induced apoptosis remains controversial. Enhances TRAIL mediated apoptosis, suggesting that it might play a role in immune-mediated liver cell injury. Seric core protein is able to bind C1QR1 at the T-cell surface, resulting in down-regulation of T-lymphocytes proliferation. May transactivate human MYC, Rous sarcoma virus LTR, and SV40 promoters. May suppress the human FOS and HIV-1 LTR activity. Alters lipid metabolism by interacting with hepatocellular proteins involved in lipid accumulation and storage. Core protein induces up-regulation of FAS promoter activity, and thereby probably contributes to the increased triglyceride accumulation in hepatocytes (steatosis) (By similarity).
♦ E1 and E2 glycoproteins form a heterodimer that is involved in virus attachment to the host cell, virion internalization through clathrin-dependent endocytosis and fusion with host membrane. E1/E2 heterodimer binds to human LDLR, CD81 and SCARB1/SR-BI receptors, but this binding is not sufficient for infection, some additional liver specific cofactors may be needed. The fusion function may possibly be carried by E1. E2 inhibits human EIF2AK2/PKR activation, preventing the establishment of an antiviral state. E2 is a viral ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on liver sinusoidal endothelial cells and macrophage-like cells of lymph node sinuses. These interactions allow capture of circulating HCV particles by these cells and subsequent transmission to permissive cells. DCs act as sentinels in various tissues where they entrap pathogens and convey them to local lymphoid tissue or lymph node for establishment of immunity. Capture of circulating HCV particles by these SIGN+ cells may facilitate virus infection of proximal hepatocytes and lymphocyte subpopulations and may be essential for the establishment of persistent infection (By similarity).

♦ Core protein p21: Host endoplasmic reticulum membrane
♦ Single-pass membrane protein . Host mitochondrion membrane
♦ Single-pass type I membrane protein . Host lipid droplet . Note=The C-terminal transmembrane domain of core protein p21 contains an ER signal leading the nascent polyprotein to the ER membrane. Only a minor proportion of core protein is present in the nucleus and an unknown proportion is secreted (By similarity). .
♦ Core protein p19: Virion . Host cytoplasm . Host nucleus . Secreted .
♦ Envelope glycoprotein E1: Virion membrane
♦ Single-pass type I membrane protein . Host endoplasmic reticulum membrane
♦ Single-pass type I membrane protein . Note=The C-terminal transmembrane domain acts as a signal sequence and forms a hairpin structure before cleavage by host signal peptidase. After cleavage, the membrane sequence is retained at the C-terminus of the protein, serving as ER membrane anchor. A reorientation of the second hydrophobic stretch occurs after cleavage producing a single reoriented transmembrane domain. These events explain the final topology of the protein. ER retention of E1 is leaky and, in overexpression conditions, only a small fraction reaches the plasma membrane (By similarity). .
♦ Envelope glycoprotein E2: Virion membrane
♦ Single-pass type I membrane protein . Host endoplasmic reticulum membrane
♦ Single-pass type I membrane protein . Note=The C-terminal transmembrane domain acts as a signal sequence and forms a hairpin structure before cleavage by host signal peptidase. After cleavage, the membrane sequence is retained at the C-terminus of the protein, serving as ER membrane anchor. A reorientation of the second hydrophobic stretch occurs after cleavage producing a single reoriented transmembrane domain. These events explain the final topology of the protein. ER retention of E2 is leaky and, in overexpression conditions, only a small fraction reaches the plasma membrane (By similarity). .

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