Protein: POLG_HCVH4
Sequence: MSTNPKPQRKTKRNTNRRPQDVKFPGGGQIVGGVYLLTRRGPRLGVRATRKTSERSQPRGRRQPIPKARRPEGRAWAQPGYPWPLYGNEGLGWAGWLLSPRGSRPSWGPTDPRRRSRNLGKVIDTLTCGFADLMGYIPLVGAPLGGASRALAHGVRVLEDGVNYATGNLPGCSFSIFLSALMSCLTAPASAYEVRNVSGIYHVTNDCSNSSIAYEAAGMIMHTPGCVPCVREDNSSRCWVALTPTLAARNASVPTTTIRRHVDLLVGAATLCSAMYVGDLCGSVFLVSQLITFSPRRYETVQDCNCSLYPGHVSGHRMAWDMMMNWSPTAALVVSQLLRIPQAVVDIVAGAHWGVLAGLAYYPMVGNWAKVLIVMLLFAGVDGANTHTVGGTEGFTTQRFTSLFTLGPSQKIQLINTNGSWHINRTALNCNDSFKTGFLAALFYVHKFNASGCPEHMASCRPIDKFDQGWGPVTYAEPSISEQRPYCWHYAPRPCGTIPASEVCGPVYCFTPSPVVVGTTDRF
What is the function of this protein?
Forms a heterodimer with envelope glycoprotein E1, which mediates virus attachment to the host cell, virion internalization through clathrin-dependent endocytosis and fusion with host membrane (By similarity).  Fusion with the host cell is most likely mediated by both E1 and E2, through conformational rearrangements of the heterodimer required for fusion rather than a classical class II fusion mechanism (By similarity).  The interaction between envelope glycoprotein E2 and host apolipoprotein E/APOE allows the proper assembly, maturation and infectivity of the viral particles (By similarity).  This interaction is probably promoted via the up-regulation of cellular autophagy by the virus (By similarity).  E1/E2 heterodimer binds host apolipoproteins such as APOB and APOE thereby forming a lipo-viro-particle (LVP) (By similarity).  APOE associated to the LVP allows the initial virus attachment to cell surface receptors such as the heparan sulfate proteoglycans (HSPGs), syndecan-1 (SDC1), syndecan-1 (SDC2), the low-density lipoprotein receptor (LDLR) and scavenger receptor class B type I (SCARB1) (By similarity).  The cholesterol transfer activity of SCARB1 allows E2 exposure and binding of E2 to SCARB1 and the tetraspanin CD81 (By similarity).  E1/E2 heterodimer binding on CD81 activates the epithelial growth factor receptor (EGFR) signaling pathway (By similarity).  Diffusion of the complex E1-E2-EGFR-SCARB1-CD81 to the cell lateral membrane allows further interaction with Claudin 1 (CLDN1) and occludin (OCLN) to finally trigger HCV entry (By similarity).  Inhibits host EIF2AK2/PKR activation, preventing the establishment of an antiviral state (By similarity).  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 (By similarity).  These interactions allow the capture of circulating HCV particles by these cells and subsequent facilitated transmission to permissive cells such as hepatocytes and lymphocyte subpopulations (By similarity).
What are the official names of this protein?
Genome polyprotein.
What is the protein family that this protein belongs to?
Belongs to the hepacivirus polyprotein family.
What are the subcellular locations of this protein?
[Core protein precursor]: Host endoplasmic reticulum membrane; Single-pass membrane protein. Host mitochondrion membrane; Single-pass type I membrane protein. Note=The C-terminal transmembrane domain of the core protein precursor contains an ER signal leading the nascent polyprotein to the ER membrane. SUBCELLULAR LOCATION: [Mature core protein]: Virion. Host cytoplasm. Host nucleus. Host lipid droplet. Note=Only a minor proportion of core protein is present in the nucleus (By similarity). Probably present on the surface of lipid droplets (By similarity). SUBCELLULAR LOCATION: [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 (By similarity). After cleavage, the membrane sequence is retained at the C-terminus of the protein, serving as ER membrane anchor (By similarity). A reorientation of the second hydrophobic stretch occurs after cleavage producing a single reoriented transmembrane domain (By similarity). These events explain the final topology of the protein (By similarity). SUBCELLULAR LOCATION: [Envelope glycoprotein E2]: Virion membrane; Single-pass type I membrane protein. Host endoplasmic reticulum membrane; Single-pass type I membrane protein. Host lipid droplet. Note=The C-terminal transmembrane domain acts as a signal sequence and forms a hairpin structure before cleavage by host signal peptidase (By similarity). After cleavage, the membrane sequence is retained at the C-terminus of the protein, serving as ER membrane anchor (By similarity). A reorientation of the second hydrophobic stretch occurs after cleavage producing a single reoriented transmembrane domain (By similarity). These events explain the final topology of the protein (By similarity).