FEATURES

FAMILY

lentivirus primate group Nef protein family

DESCRIPTION

Also known as NEF_HV1B1, nef. Factor of infectivity and pathogenicity, required for optimal virus replication. Alters numerous pathways of T-lymphocytes function and down-regulates immunity surface molecules in order to evade host defense and increase viral infectivity. Alters the functionality of other immunity cells, like dendritic cells, monocytes/macrophages and NK cells., In infected CD4(+) T-lymphocytes, down-regulates the surface MHC-I, mature MHC-II, CD4, CD28, CCR5 and CXCR4 molecules. Mediates internalization and degradation of host CD4 through the interaction of with the cytoplasmic tail of CD4, the recruitment of AP-2 (clathrin adapter protein complex 2), internalization through clathrin coated pits, and subsequent transport to endosomes and lysosomes for degradation. Diverts host MHC-I molecules to the trans-Golgi network-associated endosomal compartments by an endocytic pathway to finally target them for degradation. MHC-I down-regulation may involve AP-1 (clathrin adapter protein complex 1) or possibly Src family kinase-ZAP70/Syk-PI3K cascade recruited by PACS2. In consequence infected cells are masked for immune recognition by cytotoxic T-lymphocytes. Decreasing the number of immune receptors also prevents reinfection by more HIV particles (superinfection). Down-regulates host SERINC3 and SERINC5 thereby excluding these proteins from the viral particles. Virion infectivity is drastically higher when SERINC3 or SERINC5 are excluded from the viral envelope, because these host antiviral proteins impare the membrane fusion event necessary for subsequent virion penetration., Bypasses host T-cell signaling by inducing a transcriptional program nearly identical to that of anti-CD3 cell activation. Interaction with TCR-zeta chain up-regulates the Fas ligand (FasL). Increasing surface FasL molecules and decreasing surface MHC-I molecules on infected CD4(+) cells send attacking cytotoxic CD8+ T-lymphocytes into apoptosis., Plays a role in optimizing the host cell environment for viral replication without causing cell death by apoptosis. Protects the infected cells from apoptosis in order to keep them alive until the next virus generation is ready to strike. Inhibits the Fas and TNFR-mediated death signals by blocking MAP3K5/ASK1. Decreases the half-life of TP53, protecting the infected cell against p53-mediated apoptosis. Inhibits the apoptotic signals regulated by the Bcl-2 family proteins through the formation of a Nef/PI3-kinase/PAK2 complex that leads to activation of PAK2 and induces phosphorylation of host BAD., Extracellular Nef protein targets CD4(+) T-lymphocytes for apoptosis by interacting with CXCR4 surface receptors. Monomer; cytosolic form. Homodimer; membrane bound form. Interacts with Nef associated p21-activated kinase (PAK2); this interaction activates PAK2. Associates with the Nef-MHC-I-AP1 complex; this complex is required for MHC-I internalization. Interacts (via C-terminus) with host PI3-kinase. Interacts with host PACS1; this interaction seems to be weak. Interacts with host PACS2. Interacts with host LCK and MAPK3; these interactions inhibit the kinase activity of the latters. Interacts with host ATP6V1H; this interaction may play a role in CD4 endocytosis. Associates with the CD4-Nef-AP2 complex; this complex is required for CD4 internalization. Interacts with host AP2 subunit alpha and AP2 subunit sigma2. Interacts with TCR-zeta chain; this interaction up-regulates the Fas ligand (FasL) surface expression. Interacts with host HCK, LYN, and SRC; these interactions activate the Src family kinases. Interacts with MAP3K5; this interaction inhibits the Fas and TNFR-mediated death signals. Interacts with beta-COP and PTE1. Interacts with human RACK1; this increases Nef phosphorylation by PKC. Interacts with TP53; this interaction decreases the half-life of TP53, protecting the infected cell against p53-mediated apoptosis.

EXTERNAL LINKS

nef

Protein Nef

nef

Molecular Synopsis