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== Function == | == Function == | ||
[[http://www.uniprot.org/uniprot/NEF_HV1A2 NEF_HV1A2]] 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. One of the earliest and most abundantly expressed viral proteins (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> 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) (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> 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 (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> 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. Interacts and decreases the half-life of p53, 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 Bad (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> Extracellular Nef protein targets CD4(+) T-lymphocytes for apoptosis by interacting with CXCR4 surface receptors (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> [[http://www.uniprot.org/uniprot/HCK_HUMAN HCK_HUMAN]] Non-receptor tyrosine-protein kinase found in hematopoietic cells that transmits signals from cell surface receptors and plays an important role in the regulation of innate immune responses, including neutrophil, monocyte, macrophage and mast cell functions, phagocytosis, cell survival and proliferation, cell adhesion and migration. Acts downstream of receptors that bind the Fc region of immunoglobulins, such as FCGR1A and FCGR2A, but also CSF3R, PLAUR, the receptors for IFNG, IL2, IL6 and IL8, and integrins, such as ITGB1 and ITGB2. During the phagocytic process, mediates mobilization of secretory lysosomes, degranulation, and activation of NADPH oxidase to bring about the respiratory burst. Plays a role in the release of inflammatory molecules. Promotes reorganization of the actin cytoskeleton and actin polymerization, formation of podosomes and cell protrusions. Inhibits TP73-mediated transcription activation and TP73-mediated apoptosis. Phosphorylates CBL in response to activation of immunoglobulin gamma Fc region receptors. Phosphorylates ADAM15, BCR, ELMO1, FCGR2A, GAB1, GAB2, RAPGEF1, STAT5B, TP73, VAV1 and WAS.<ref>PMID:8132624</ref> <ref>PMID:7535819</ref> <ref>PMID:9406996</ref> <ref>PMID:9407116</ref> <ref>PMID:10092522</ref> <ref>PMID:10779760</ref> <ref>PMID:10973280</ref> <ref>PMID:12411494</ref> <ref>PMID:11741929</ref> <ref>PMID:11904303</ref> <ref>PMID:11896602</ref> <ref>PMID:15010462</ref> <ref>PMID:15952790</ref> <ref>PMID:15998323</ref> <ref>PMID:17535448</ref> <ref>PMID:17310994</ref> <ref>PMID:19114024</ref> <ref>PMID:19903482</ref> <ref>PMID:20452982</ref> | [[http://www.uniprot.org/uniprot/NEF_HV1A2 NEF_HV1A2]] 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. One of the earliest and most abundantly expressed viral proteins (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> 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) (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> 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 (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> 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. Interacts and decreases the half-life of p53, 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 Bad (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> Extracellular Nef protein targets CD4(+) T-lymphocytes for apoptosis by interacting with CXCR4 surface receptors (By similarity).<ref>PMID:9218412</ref> <ref>PMID:10224289</ref> <ref>PMID:10208934</ref> <ref>PMID:11070003</ref> <ref>PMID:11420046</ref> <ref>PMID:11689886</ref> [[http://www.uniprot.org/uniprot/HCK_HUMAN HCK_HUMAN]] Non-receptor tyrosine-protein kinase found in hematopoietic cells that transmits signals from cell surface receptors and plays an important role in the regulation of innate immune responses, including neutrophil, monocyte, macrophage and mast cell functions, phagocytosis, cell survival and proliferation, cell adhesion and migration. Acts downstream of receptors that bind the Fc region of immunoglobulins, such as FCGR1A and FCGR2A, but also CSF3R, PLAUR, the receptors for IFNG, IL2, IL6 and IL8, and integrins, such as ITGB1 and ITGB2. During the phagocytic process, mediates mobilization of secretory lysosomes, degranulation, and activation of NADPH oxidase to bring about the respiratory burst. Plays a role in the release of inflammatory molecules. Promotes reorganization of the actin cytoskeleton and actin polymerization, formation of podosomes and cell protrusions. Inhibits TP73-mediated transcription activation and TP73-mediated apoptosis. Phosphorylates CBL in response to activation of immunoglobulin gamma Fc region receptors. Phosphorylates ADAM15, BCR, ELMO1, FCGR2A, GAB1, GAB2, RAPGEF1, STAT5B, TP73, VAV1 and WAS.<ref>PMID:8132624</ref> <ref>PMID:7535819</ref> <ref>PMID:9406996</ref> <ref>PMID:9407116</ref> <ref>PMID:10092522</ref> <ref>PMID:10779760</ref> <ref>PMID:10973280</ref> <ref>PMID:12411494</ref> <ref>PMID:11741929</ref> <ref>PMID:11904303</ref> <ref>PMID:11896602</ref> <ref>PMID:15010462</ref> <ref>PMID:15952790</ref> <ref>PMID:15998323</ref> <ref>PMID:17535448</ref> <ref>PMID:17310994</ref> <ref>PMID:19114024</ref> <ref>PMID:19903482</ref> <ref>PMID:20452982</ref> | ||
| + | <div style="background-color:#fffaf0;"> | ||
| + | == Publication Abstract from PubMed == | ||
| + | HIV-1 Nef supports high-titer viral replication in vivo and is essential for AIDS progression. Nef function depends on interactions with multiple host cell effectors, including Hck and other Src-family kinases. Here we describe the X-ray crystal structure of Nef in complex with the Hck SH3-SH2 regulatory region to a resolution of 1.86 A. The complex crystallized as a dimer of complexes, with the conserved Nef PxxPxR motif engaging the Hck SH3 domain. A new intercomplex contact was found between SH3 Glu93 and Nef Arg105. Mutagenesis of Hck SH3 E93 interfered with Nef:Hck complex formation and kinase activation in cells. The Hck SH2 domains impinge on the N-terminal region of Nef to stabilize a dimer conformation that exposes Asp123, a residue critical for Nef function. Our results suggest that in addition to serving as a kinase effector for Nef, Hck binding may reorganize the Nef dimer for functional interaction with other signaling partners. | ||
| + | |||
| + | Interaction with the SH3-SH2 region of the Src-family kinase Hck structures the HIV-1 Nef dimer for kinase activation and effector recruitment.,Alvarado JJ, Tarafdar S, Yeh JI, Smithgall TE J Biol Chem. 2014 Aug 13. pii: jbc.M114.600031. PMID:25122770<ref>PMID:25122770</ref> | ||
| + | |||
| + | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | ||
| + | </div> | ||
== References == | == References == | ||
<references/> | <references/> | ||
Revision as of 05:43, 27 August 2014
Crystal Structure of HIV-1 Nef-SF2 Core Domain in Complex with the Src Family Kinase Hck SH3-SH2 Tandem Regulatory Domains
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