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Volumn 140, Issue 2, 1998, Pages 315-323

Dilation of the human immunodeficiency virus-1 envelope glycoprotein fusion pore revealed by the inhibitory action of a synthetic peptide from gp41

Author keywords

[No Author keywords available]

Indexed keywords

AMINO ACID; CD4 ANTIGEN; GLYCOPROTEIN GP 120; GLYCOPROTEIN GP 41; LIPID; SYNTHETIC PEPTIDE; VIRUS ENVELOPE PROTEIN;

EID: 0038065763     PISSN: 00219525     EISSN: None     Source Type: Journal    
DOI: 10.1083/jcb.140.2.315     Document Type: Article
Times cited : (270)

References (49)
  • 2
    • 0023914996 scopus 로고
    • Cooperativity in viral fusion
    • Blumenthal, R. 1988. Cooperativity in viral fusion. Cell. Biophys. 12:1-12.
    • (1988) Cell. Biophys. , vol.12 , pp. 1-12
    • Blumenthal, R.1
  • 3
    • 0003110115 scopus 로고    scopus 로고
    • Membrane fusion
    • J.F. Hoffman, and J.C. Jamieson, editors. Oxford University Press, New York
    • Blumenthal, R., and D.S. Dimitrov. 1997. Membrane fusion. In Handbook of Physiology. J.F. Hoffman, and J.C. Jamieson, editors. Oxford University Press, New York. 569-604.
    • (1997) Handbook of Physiology , pp. 569-604
    • Blumenthal, R.1    Dimitrov, D.S.2
  • 4
    • 0026389193 scopus 로고
    • A dissection of steps leading to viral envelope protein-mediated membrane fusion
    • Blumenthal, R., C. Schoch, A. Puri, and M.J. Clague. 1991. A dissection of steps leading to viral envelope protein-mediated membrane fusion. Ann. NY Acad. Sci. 635:285-296.
    • (1991) Ann. NY Acad. Sci. , vol.635 , pp. 285-296
    • Blumenthal, R.1    Schoch, C.2    Puri, A.3    Clague, M.J.4
  • 6
    • 0029823936 scopus 로고    scopus 로고
    • Dilation of the influenza hemagglutinin fusion pore revealed by the kinetics of individual cell-cell fusion events
    • Blumenthal, R., D.P. Sarkar, S. Durell, D.E. Howard, and S.J. Morris. 1996. Dilation of the influenza hemagglutinin fusion pore revealed by the kinetics of individual cell-cell fusion events. J. Cell Biol. 135:63-71.
    • (1996) J. Cell Biol. , vol.135 , pp. 63-71
    • Blumenthal, R.1    Sarkar, D.P.2    Durell, S.3    Howard, D.E.4    Morris, S.J.5
  • 7
    • 0029079641 scopus 로고
    • Fusogenic selectivity of the envelope glycoprotein is a major determinant of human immunodeficiency virus type 1 tropism for CD4+ T-cell lines vs. primary macrophages
    • Broder, C.C., and E.A. Berger. 1995. Fusogenic selectivity of the envelope glycoprotein is a major determinant of human immunodeficiency virus type 1 tropism for CD4+ T-cell lines vs. primary macrophages. Proc. Natl. Acad. Sci. USA. 92:9004-9008.
    • (1995) Proc. Natl. Acad. Sci. USA , vol.92 , pp. 9004-9008
    • Broder, C.C.1    Berger, E.A.2
  • 8
    • 0028023726 scopus 로고
    • Structure of influenza haemagglutinin at the pH of membrane fusion
    • Bullough, P.A., F.M. Hughson, J.J. Skehel, and D.C. Wiley. 1994. Structure of influenza haemagglutinin at the pH of membrane fusion. Nature. 371: 37-43.
    • (1994) Nature , vol.371 , pp. 37-43
    • Bullough, P.A.1    Hughson, F.M.2    Skehel, J.J.3    Wiley, D.C.4
  • 9
    • 0027253445 scopus 로고
    • A spring-loaded mechanism for the conformational change of influenza hemagglutinin
    • Carr, C.M., and P.S. Kim. 1993. A spring-loaded mechanism for the conformational change of influenza hemagglutinin. Cell. 73:823-832.
    • (1993) Cell , vol.73 , pp. 823-832
    • Carr, C.M.1    Kim, P.S.2
  • 10
    • 0030970693 scopus 로고    scopus 로고
    • Core structure of gp41 from the HIV envelope glycoprotein
    • Chan, D.C., D. Fass, J.M. Berger, and P.S. Kim. 1997. Core structure of gp41 from the HIV envelope glycoprotein. Cell. 89:263-273.
    • (1997) Cell , vol.89 , pp. 263-273
    • Chan, D.C.1    Fass, D.2    Berger, J.M.3    Kim, P.S.4
  • 11
    • 0029072191 scopus 로고
    • A molecular clasp in the human immunodeficiency virus (HIV) type 1 TM protein determines the anti-HIV activity of gp41 derivatives: Implication for viral fusion
    • Chen, C.H., T.J. Matthews, C.B. McDanal, D.P. Bolognesi, and M.L. Greenberg. 1995. A molecular clasp in the human immunodeficiency virus (HIV) type 1 TM protein determines the anti-HIV activity of gp41 derivatives: implication for viral fusion. J. Virol. 69:3771-3777.
    • (1995) J. Virol. , vol.69 , pp. 3771-3777
    • Chen, C.H.1    Matthews, T.J.2    McDanal, C.B.3    Bolognesi, D.P.4    Greenberg, M.L.5
  • 12
    • 0023636677 scopus 로고
    • Biomembrane fusion: A new concept derived from model studies using two interacting planar lipid bilayers
    • Chernomordik, L.V., G.B. Melikyan, and Y.A. Chizmadzhev. 1987. Biomembrane fusion: a new concept derived from model studies using two interacting planar lipid bilayers. Biochim. Biophys. Acta. 906:309-352.
    • (1987) Biochim. Biophys. Acta. , vol.906 , pp. 309-352
    • Chernomordik, L.V.1    Melikyan, G.B.2    Chizmadzhev, Y.A.3
  • 13
    • 0029898564 scopus 로고    scopus 로고
    • Membrane fusion mediated by the influenza virus hemagglutinin requires the concerted action of at least three hemagglutinin trimers
    • Danieli, T., S.L. Pelletier, Y.I. Henis, and J. M. White. 1996. Membrane fusion mediated by the influenza virus hemagglutinin requires the concerted action of at least three hemagglutinin trimers. J. Cell. Biol. 133: 559-569.
    • (1996) J. Cell. Biol. , vol.133 , pp. 559-569
    • Danieli, T.1    Pelletier, S.L.2    Henis, Y.I.3    White, J.M.4
  • 14
    • 0027957288 scopus 로고
    • Photoinactivation and kinetics of membrane fusion mediated by the human immunodeficiency type 1 envelope glycoprotein
    • Dimitrov, D.S., and R. Blumenthal. 1994. Photoinactivation and kinetics of membrane fusion mediated by the human immunodeficiency type 1 envelope glycoprotein. J. Virol. 68:1956-1961.
    • (1994) J. Virol. , vol.68 , pp. 1956-1961
    • Dimitrov, D.S.1    Blumenthal, R.2
  • 15
    • 0026068529 scopus 로고
    • Biological and immunological properties of human immunodeficiency virus type 1 envelope glycoprotein: Analysis of proteins with truncations and deletions expressed by recombinant vaccinia viruses
    • Earl, P.L., S. Koenig, and B. Moss. 1991. Biological and immunological properties of human immunodeficiency virus type 1 envelope glycoprotein: analysis of proteins with truncations and deletions expressed by recombinant vaccinia viruses. J. Virol. 65:31-41.
    • (1991) J. Virol. , vol.65 , pp. 31-41
    • Earl, P.L.1    Koenig, S.2    Moss, B.3
  • 16
    • 0025109728 scopus 로고
    • Fusion of influenza hemagalutinin-expressing fibroblasts with glycophorin-bearing liposomes: Role of hemagglutinin surface density
    • Ellens, H., J. Bentz, D. Mason, F. Zhang, and J.M. White. 1990. Fusion of influenza hemagalutinin-expressing fibroblasts with glycophorin-bearing liposomes: role of hemagglutinin surface density. Biochemistry. 29:9697-9707.
    • (1990) Biochemistry , vol.29 , pp. 9697-9707
    • Ellens, H.1    Bentz, J.2    Mason, D.3    Zhang, F.4    White, J.M.5
  • 17
    • 0029914299 scopus 로고    scopus 로고
    • Retrovirus envelope domain at 1.7 angstrom resolution
    • Fass, D., S.C. Harrison, and P.S. Kim. 1996. Retrovirus envelope domain at 1.7 angstrom resolution. Nat. Struct. Biol. 3:465-469.
    • (1996) Nat. Struct. Biol. , vol.3 , pp. 465-469
    • Fass, D.1    Harrison, S.C.2    Kim, P.S.3
  • 18
    • 0030002637 scopus 로고    scopus 로고
    • HIV-1 entry cofactor: Functional cDNA cloning of a seven-transmembrane, G protein-coupled receptor
    • Feng, Y., C.C. Broder, P.E. Kennedy, and E.A. Berger. 1996. HIV-1 entry cofactor: functional cDNA cloning of a seven-transmembrane, G protein-coupled receptor. Science. 272:872-877.
    • (1996) Science , vol.272 , pp. 872-877
    • Feng, Y.1    Broder, C.C.2    Kennedy, P.E.3    Berger, E.A.4
  • 19
    • 0027173841 scopus 로고
    • Physicochemical dissociation of CD4-mediated syncytium formation and shedding of human immunodeficiency virus type 1 gp120
    • Fu, Y.K., T.K. Hart, Z.L. Jonak, and P.J. Bugelski. 1993. Physicochemical dissociation of CD4-mediated syncytium formation and shedding of human immunodeficiency virus type 1 gp120. J. Virol. 67:3818-3825.
    • (1993) J. Virol. , vol.67 , pp. 3818-3825
    • Fu, Y.K.1    Hart, T.K.2    Jonak, Z.L.3    Bugelski, P.J.4
  • 21
    • 0031962175 scopus 로고    scopus 로고
    • Conformational changes in cell surface HIV-1 envelope glycoproteins are triggered by cooperation between cell surface CD4 and coreceptors
    • Jones, P., T. Korte, and R. Blumenthal. 1998. Conformational changes in cell surface HIV-1 envelope glycoproteins are triggered by cooperation between cell surface CD4 and coreceptors. J. Biol. Chem. 273:404-409.
    • (1998) J. Biol. Chem. , vol.273 , pp. 404-409
    • Jones, P.1    Korte, T.2    Blumenthal, R.3
  • 22
    • 0028179011 scopus 로고
    • Lipid-anchored influenza hemagglutinin promotes hemifusion, not complete fusion
    • Kemble, G.W., T. Danieli, and J.M. White. 1994. Lipid-anchored influenza hemagglutinin promotes hemifusion, not complete fusion. Cell. 76:383-391.
    • (1994) Cell , vol.76 , pp. 383-391
    • Kemble, G.W.1    Danieli, T.2    White, J.M.3
  • 24
    • 0029926552 scopus 로고    scopus 로고
    • HIV-1 membrane fusion mechanism: Structural studies of the interactions between biologically-active peptides from gp41
    • Lawless, M.K., S. Barney, K.I. Guthrie, T.B. Bucy, S.R. Petteway, Jr., and G. Merutka. 1996. HIV-1 membrane fusion mechanism: structural studies of the interactions between biologically-active peptides from gp41. Biochemistry. 35:13697-13708.
    • (1996) Biochemistry , vol.35 , pp. 13697-13708
    • Lawless, M.K.1    Barney, S.2    Guthrie, K.I.3    Bucy, T.B.4    Petteway Jr., S.R.5    Merutka, G.6
  • 25
    • 0028834461 scopus 로고
    • A trimeric structural domain of the HIV-1 transmembrane glycoprotein
    • Lu, M., S.C. Blacklow, and P.S. Kim. 1995. A trimeric structural domain of the HIV-1 transmembrane glycoprotein. Nat. Struct. Biol. 2:1075-1082.
    • (1995) Nat. Struct. Biol. , vol.2 , pp. 1075-1082
    • Lu, M.1    Blacklow, S.C.2    Kim, P.S.3
  • 26
    • 0023028190 scopus 로고
    • The T4 gene encodes the AIDS virus receptor and is expressed in the immune system and the brain
    • Maddon, P.J., A.G. Dalgleish, J.S. McDougal, P.R. Clapham, R.A. Weiss, and R. Axel. 1986. The T4 gene encodes the AIDS virus receptor and is expressed in the immune system and the brain. Cell. 47:333-348.
    • (1986) Cell , vol.47 , pp. 333-348
    • Maddon, P.J.1    Dalgleish, A.G.2    McDougal, J.S.3    Clapham, P.R.4    Weiss, R.A.5    Axel, R.6
  • 27
    • 0028168944 scopus 로고
    • Structural rearrangements in the transmembrane glycoprotein after receptor binding
    • Matthews, T.J., C. Wild, C.H. Chen, D.P. Bolognesi, and M.L. Greenberg. 1994. Structural rearrangements in the transmembrane glycoprotein after receptor binding. Immunol. Rev. 140:93-104.
    • (1994) Immunol. Rev. , vol.140 , pp. 93-104
    • Matthews, T.J.1    Wild, C.2    Chen, C.H.3    Bolognesi, D.P.4    Greenberg, M.L.5
  • 28
    • 0028865392 scopus 로고
    • GPI-anchored influenza hemagglutinin induces hemifusion to both red blood cell and planar bilayer membranes
    • Melikyan, G.B., J.M. White, and F.S. Cohen. 1995. GPI-anchored influenza hemagglutinin induces hemifusion to both red blood cell and planar bilayer membranes. J. Cell Biol. 131:679-691.
    • (1995) J. Cell Biol. , vol.131 , pp. 679-691
    • Melikyan, G.B.1    White, J.M.2    Cohen, F.S.3
  • 29
    • 0030899232 scopus 로고    scopus 로고
    • Inner but not outer membrane leaflets control the transition from glycosylphosphatidylinositol-anchored influenza hemagglutinin-induced hemifusion to full fusion
    • 28a. Melikyan, G.B., S.A. Brener, D.C. Ok, and F.S. Cohen. 1997. Inner but not outer membrane leaflets control the transition from glycosylphosphatidylinositol-anchored influenza hemagglutinin-induced hemifusion to full fusion. J. Cell Biol. 136:995-1005.
    • (1997) J. Cell Biol. , vol.136 , pp. 995-1005
    • Melikyan, G.B.1    Brener, S.A.2    Ok, D.C.3    Cohen, F.S.4
  • 30
    • 0030222281 scopus 로고    scopus 로고
    • The fusion pore and mechanisms of biological membrane fusion
    • Monck, J.R., and J.M. Fernandez. 1996. The fusion pore and mechanisms of biological membrane fusion. Curr. Opin. Cell Biol. 8:524-533.
    • (1996) Curr. Opin. Cell Biol. , vol.8 , pp. 524-533
    • Monck, J.R.1    Fernandez, J.M.2
  • 32
    • 0024564649 scopus 로고
    • Kinetics of pH-dependent fusion between 3T3 fibroblasts expressing influenza hemagglutinin and red blood cells. Measurement by dequenching of fluorescence
    • Morris, S.J., D.P. Sarkar, J.M. White, and R. Blumenthal. 1989. Kinetics of pH-dependent fusion between 3T3 fibroblasts expressing influenza hemagglutinin and red blood cells. Measurement by dequenching of fluorescence. J. Biol. Chem. 264:3972-3978.
    • (1989) J. Biol. Chem. , vol.264 , pp. 3972-3978
    • Morris, S.J.1    Sarkar, D.P.2    White, J.M.3    Blumenthal, R.4
  • 33
    • 0028129959 scopus 로고
    • Fusogenic mechanisms of enveloped-virus glycoproteins analyzed by a novel recombinant vaccinia virus-based assay quantitating cell fusion-dependent reporter gene activation
    • Nussbaum, O., C.C. Broder, and E.A. Berger. 1994. Fusogenic mechanisms of enveloped-virus glycoproteins analyzed by a novel recombinant vaccinia virus-based assay quantitating cell fusion-dependent reporter gene activation. J. Virol. 68:5411-5422.
    • (1994) J. Virol. , vol.68 , pp. 5411-5422
    • Nussbaum, O.1    Broder, C.C.2    Berger, E.A.3
  • 34
    • 0029980139 scopus 로고    scopus 로고
    • Heat-resistant factors in human erythrocyte membranes mediate CD4-dependent fusion with cells expressing HIV-1 envelope glycoproteins
    • Puri, A., S.J. Morris, P. Jones, M. Ryan, and R. Blumenthal. 1996. Heat-resistant factors in human erythrocyte membranes mediate CD4-dependent fusion with cells expressing HIV-1 envelope glycoproteins. Virology. 219:262-267.
    • (1996) Virology , vol.219 , pp. 262-267
    • Puri, A.1    Morris, S.J.2    Jones, P.3    Ryan, M.4    Blumenthal, R.5
  • 35
    • 0024406233 scopus 로고
    • Initial stages of influenza hemagglutinin-induced cell fusion monitored simultaneously by two fluorescent events: Cytoplasmic continuity and lipid mixing
    • Sarkar, D.P., S.J. Morris, O. Eidelman, J. Zimmerberg, and R. Blumenthal. 1989. Initial stages of influenza hemagglutinin-induced cell fusion monitored simultaneously by two fluorescent events: Cytoplasmic continuity and lipid mixing. J. Cell Biol. 109:113-122.
    • (1989) J. Cell Biol. , vol.109 , pp. 113-122
    • Sarkar, D.P.1    Morris, S.J.2    Eidelman, O.3    Zimmerberg, J.4    Blumenthal, R.5
  • 36
    • 0025866185 scopus 로고
    • Conformational changes induced in the human immunodeficiency virus envelope glycoprotein by soluble CD4 binding
    • Sattentau, Q.J., and J.P. Moore. 1991. Conformational changes induced in the human immunodeficiency virus envelope glycoprotein by soluble CD4 binding. J. Exp. Med. 174:407-415.
    • (1991) J. Exp. Med. , vol.174 , pp. 407-415
    • Sattentau, Q.J.1    Moore, J.P.2
  • 37
    • 0027190432 scopus 로고
    • Role of the fusion peptide sequence in initial stages of influenza hemagglutinin-induced cell fusion
    • Schoch, C., and R. Blumenthal. 1993. Role of the fusion peptide sequence in initial stages of influenza hemagglutinin-induced cell fusion. J. Biol. Chem. 268:9267-9274.
    • (1993) J. Biol. Chem. , vol.268 , pp. 9267-9274
    • Schoch, C.1    Blumenthal, R.2
  • 38
    • 0024331657 scopus 로고
    • Patch clamp studies of single cell-fusion events mediated by a viral fusion protein
    • Spruce, A.E., A. Iwata, J.M. White, and W. Almers. 1989. Patch clamp studies of single cell-fusion events mediated by a viral fusion protein. Nature. 342:555-558.
    • (1989) Nature , vol.342 , pp. 555-558
    • Spruce, A.E.1    Iwata, A.2    White, J.M.3    Almers, W.4
  • 39
    • 0025075412 scopus 로고
    • Oligomeric organization of gp120 on infectious human immunodeficiency virus type 1 particles
    • Weiss, C.D., J.A. Levy, and J.M. White. 1990. Oligomeric organization of gp120 on infectious human immunodeficiency virus type 1 particles. J. Virol. 64:5674-5677.
    • (1990) J. Virol. , vol.64 , pp. 5674-5677
    • Weiss, C.D.1    Levy, J.A.2    White, J.M.3
  • 40
    • 0029864284 scopus 로고    scopus 로고
    • Studies of HIV-1 envelope glycoprotein-mediated fusion using a simple fluorescence assay
    • Weiss, C.D., S.W. Barnett, N. Cacalano, N. Killeen, D.R. Littman, and J.M. White. 1996. Studies of HIV-1 envelope glycoprotein-mediated fusion using a simple fluorescence assay. AIDS. 10:241-246.
    • (1996) AIDS , vol.10 , pp. 241-246
    • Weiss, C.D.1    Barnett, S.W.2    Cacalano, N.3    Killeen, N.4    Littman, D.R.5    White, J.M.6
  • 41
    • 0029878665 scopus 로고    scopus 로고
    • The ectodomain of HIV-1 env subunit gp41 forms a soluble, alpha-helical, rod-like oligomer in the absence of gp120 and the N-terminal fusion peptide
    • Weissenhorn, W., S.A. Wharton, L.J. Calder, P.L. Earl, B. Moss, E. Aliprandis, J.J. Skehel, and D.C. Wiley. 1996. The ectodomain of HIV-1 env subunit gp41 forms a soluble, alpha-helical, rod-like oligomer in the absence of gp120 and the N-terminal fusion peptide. EMBO (Eur. Mol. Biol. Organ.) J. 15:1507-1514.
    • (1996) EMBO (Eur. Mol. Biol. Organ.) J. , vol.15 , pp. 1507-1514
    • Weissenhorn, W.1    Wharton, S.A.2    Calder, L.J.3    Earl, P.L.4    Moss, B.5    Aliprandis, E.6    Skehel, J.J.7    Wiley, D.C.8
  • 43
    • 0026492542 scopus 로고
    • Membrane fusion
    • White, J.M. 1992. Membrane fusion. Science. 258:917-924.
    • (1992) Science , vol.258 , pp. 917-924
    • White, J.M.1
  • 45
    • 0026465468 scopus 로고
    • A synthetic peptide inhibitor of human immunodeficiency virus replication: Correlation between solution structure and viral inhibition
    • Wild, C., T. Oas, C. McDanal, D. Bolognesi, and T. Matthews. 1992. A synthetic peptide inhibitor of human immunodeficiency virus replication: correlation between solution structure and viral inhibition. Proc. Natl. Acad. Sci. USA. 89:10537-10541.
    • (1992) Proc. Natl. Acad. Sci. USA , vol.89 , pp. 10537-10541
    • Wild, C.1    Oas, T.2    McDanal, C.3    Bolognesi, D.4    Matthews, T.5
  • 46
    • 0027692502 scopus 로고
    • A synthetic peptide from HIV-1 gp41 is a potent inhibitor of virus-mediated cell-cell fusion
    • Wild, C., T. Greenwell, and T. Matthews. 1993. A synthetic peptide from HIV-1 gp41 is a potent inhibitor of virus-mediated cell-cell fusion. AIDS Res. Hum. Retroviruses. 9:1051-1053.
    • (1993) AIDS Res. Hum. Retroviruses , vol.9 , pp. 1051-1053
    • Wild, C.1    Greenwell, T.2    Matthews, T.3
  • 47
    • 0027959493 scopus 로고
    • Peptides corresponding to a predictive alpha-helical domain of human immunodeficiency virus type 1 gp41 are potent inhibitors of virus infection
    • Wild, C.T., D.C. Shugars, T.K. Greenwell, C.B. McDanal, and T.J. Matthews. 1994. Peptides corresponding to a predictive alpha-helical domain of human immunodeficiency virus type 1 gp41 are potent inhibitors of virus infection. Proc. Natl. Acad. Sci. USA. 91:9770-9774.
    • (1994) Proc. Natl. Acad. Sci. USA , vol.91 , pp. 9770-9774
    • Wild, C.T.1    Shugars, D.C.2    Greenwell, T.K.3    McDanal, C.B.4    Matthews, T.J.5
  • 48
    • 0028953212 scopus 로고
    • The inhibitory activity of an HIV type 1 peptide correlates with its ability to interact with a leucine zipper structure
    • Wild. C., T. Greenwell, D. Shugars, L. Rimsky-Clarke, and T. Matthews. 1995. The inhibitory activity of an HIV type 1 peptide correlates with its ability to interact with a leucine zipper structure. AIDS Res. Hum. Retroviruses. 11:323-325.
    • (1995) AIDS Res. Hum. Retroviruses , vol.11 , pp. 323-325
    • Wild, C.1    Greenwell, T.2    Shugars, D.3    Rimsky-Clarke, L.4    Matthews, T.5
  • 49
    • 0028587209 scopus 로고
    • Restricted movement of lipid and aqueous dyes through pores formed by influenza hemagglutinin during cell fusion
    • Zimmerberg, J., R. Blumenthal, D.P. Sarkar, M. Curran, and S.J. Morris. 1994. Restricted movement of lipid and aqueous dyes through pores formed by influenza hemagglutinin during cell fusion. J. Cell Biol. 127: 1885-1894.
    • (1994) J. Cell Biol. , vol.127 , pp. 1885-1894
    • Zimmerberg, J.1    Blumenthal, R.2    Sarkar, D.P.3    Curran, M.4    Morris, S.J.5


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