2eia Citations

Model for lentivirus capsid core assembly based on crystal dimers of EIAV p26.

J Mol Biol 286 83-93 (1999)
Cited: 95 times
EuropePMC logo PMID: 9931251

Abstract

Two crystal forms of recombinant p26 capsid protein (CA) from the equine infectious anemia virus (EIAV) have in common an antiparallel four-helix bundle dimer interface between N-terminal domains (NTDs). The dimer interface provides a lenient scaffold to accommodate the wide sequence variation in these helices within lentivirus CA. Pairs of dimers weakly associate to form exact or approximate D2 symmetry tetramers. In one of the two crystal forms, the tetramers are linked via dimerization of C-terminal domains (CTDs). We propose that the observed NTD and CTD homodimer interactions are involved in the assembly of the lentivirus capsid. The NTD homodimer shape readily suggests a model for the mature capsid core, based on hexagonal packing with dimensions and surface topology resembling described EIAV capsid cores. Combining available data for human immunodeficiency virus and EIAV CA, we also propose an assembly pathway for maturation of the lentivirus capsid core following proteolytic cleavage of the gag polyprotein precursor.

Reviews - 2eia mentioned but not cited (1)

  1. Advances to tackle backbone flexibility in protein docking. Harmalkar A, Gray JJ. Curr Opin Struct Biol 67 178-186 (2021)

Articles - 2eia mentioned but not cited (8)

  1. Design and characterization of epitope-scaffold immunogens that present the motavizumab epitope from respiratory syncytial virus. McLellan JS, Correia BE, Chen M, Yang Y, Graham BS, Schief WR, Kwong PD. J. Mol. Biol. 409 853-866 (2011)
  2. The maturational refolding of the β-hairpin motif of equine infectious anemia virus capsid protein extends its helix α1 at capsid assembly locus. Chen K, Piszczek G, Carter C, Tjandra N. J. Biol. Chem. 288 1511-1520 (2013)
  3. Binding of the C-terminal domain of the HIV-1 capsid protein to lipid membranes: a biophysical characterization. Barrera FN, Hurtado-Gómez E, Lidón-Moya MC, Neira JL. Biochem. J. 394 345-353 (2006)
  4. Protein flexibility: coordinate uncertainties and interpretation of structural differences. Rashin AA, Rashin AH, Jernigan RL. Acta Crystallogr. D Biol. Crystallogr. 65 1140-1161 (2009)
  5. MxB Restricts HIV-1 by Targeting the Tri-hexamer Interface of the Viral Capsid. Smaga SS, Xu C, Summers BJ, Digianantonio KM, Perilla JR, Xiong Y. Structure 27 1234-1245.e5 (2019)
  6. Crystal Structure of the Full-Length Feline Immunodeficiency Virus Capsid Protein Shows an N-Terminal β-Hairpin in the Absence of N-Terminal Proline. Folio C, Sierra N, Dujardin M, Alvarez G, Guillon C. Viruses 9 (2017)
  7. Determining interdomain structure and dynamics of a retroviral capsid protein in the presence of oligomerization: implication for structural transition in capsid assembly. Chen K, Tjandra N. Biochemistry 52 5365-5371 (2013)
  8. Structures of immature EIAV Gag lattices reveal a conserved role for IP6 in lentivirus assembly. Dick RA, Xu C, Morado DR, Kravchuk V, Ricana CL, Lyddon TD, Broad AM, Feathers JR, Johnson MC, Vogt VM, Perilla JR, Briggs JAG, Schur FKM. PLoS Pathog. 16 e1008277 (2020)


Reviews citing this publication (6)

  1. The structural biology of HIV assembly. Ganser-Pornillos BK, Yeager M, Sundquist WI. Curr. Opin. Struct. Biol. 18 203-217 (2008)
  2. Assembly and architecture of HIV. Ganser-Pornillos BK, Yeager M, Pornillos O. Adv. Exp. Med. Biol. 726 441-465 (2012)
  3. Structural constraints on viral escape from HIV- and SIV-specific cytotoxic T-lymphocytes. Peyerl FW, Barouch DH, Letvin NL. Viral Immunol. 17 144-151 (2004)
  4. Towards the structure of the human immunodeficiency virus: divide and conquer. Wilk T, Fuller SD. Curr. Opin. Struct. Biol. 9 231-243 (1999)
  5. FIV Gag: virus assembly and host-cell interactions. Luttge BG, Freed EO. Vet. Immunol. Immunopathol. 134 3-13 (2010)
  6. Properties and Functions of Feline Immunodeficiency Virus Gag Domains in Virion Assembly and Budding. González SA, Affranchino JL. Viruses 10 (2018)

Articles citing this publication (80)

  1. Clustered mutations in HIV-1 gag are consistently required for escape from HLA-B27-restricted cytotoxic T lymphocyte responses. Kelleher AD, Long C, Holmes EC, Allen RL, Wilson J, Conlon C, Workman C, Shaunak S, Olson K, Goulder P, Brander C, Ogg G, Sullivan JS, Dyer W, Jones I, McMichael AJ, Rowland-Jones S, Phillips RE. J. Exp. Med. 193 375-386 (2001)
  2. Image reconstructions of helical assemblies of the HIV-1 CA protein. Li S, Hill CP, Sundquist WI, Finch JT. Nature 407 409-413 (2000)
  3. Functional surfaces of the human immunodeficiency virus type 1 capsid protein. von Schwedler UK, Stray KM, Garrus JE, Sundquist WI. J. Virol. 77 5439-5450 (2003)
  4. X-ray structures of the hexameric building block of the HIV capsid. Pornillos O, Ganser-Pornillos BK, Kelly BN, Hua Y, Whitby FG, Stout CD, Sundquist WI, Hill CP, Yeager M. Cell 137 1282-1292 (2009)
  5. Assembly properties of the human immunodeficiency virus type 1 CA protein. Ganser-Pornillos BK, von Schwedler UK, Stray KM, Aiken C, Sundquist WI. J. Virol. 78 2545-2552 (2004)
  6. Structure of full-length HIV-1 CA: a model for the mature capsid lattice. Ganser-Pornillos BK, Cheng A, Yeager M. Cell 131 70-79 (2007)
  7. Atomic-level modelling of the HIV capsid. Pornillos O, Ganser-Pornillos BK, Yeager M. Nature 469 424-427 (2011)
  8. High-resolution structure of a retroviral capsid hexameric amino-terminal domain. Mortuza GB, Haire LF, Stevens A, Smerdon SJ, Stoye JP, Taylor IA. Nature 431 481-485 (2004)
  9. Head-to-tail dimers and interdomain flexibility revealed by the crystal structure of HIV-1 capsid protein (p24) complexed with a monoclonal antibody Fab. Berthet-Colominas C, Monaco S, Novelli A, Sibaï G, Mallet F, Cusack S. EMBO J. 18 1124-1136 (1999)
  10. Three-dimensional structure of HIV-1 virus-like particles by electron cryotomography. Benjamin J, Ganser-Pornillos BK, Tivol WF, Sundquist WI, Jensen GJ. J. Mol. Biol. 346 577-588 (2005)
  11. Biochemical characterization of a recombinant TRIM5alpha protein that restricts human immunodeficiency virus type 1 replication. Langelier CR, Sandrin V, Eckert DM, Christensen DE, Chandrasekaran V, Alam SL, Aiken C, Olsen JC, Kar AK, Sodroski JG, Sundquist WI. J. Virol. 82 11682-11694 (2008)
  12. Solution structure and dynamics of the Rous sarcoma virus capsid protein and comparison with capsid proteins of other retroviruses. Campos-Olivas R, Newman JL, Summers MF. J. Mol. Biol. 296 633-649 (2000)
  13. Species-specific tropism determinants in the human immunodeficiency virus type 1 capsid. Hatziioannou T, Cowan S, Von Schwedler UK, Sundquist WI, Bieniasz PD. J. Virol. 78 6005-6012 (2004)
  14. Nucleoporin NUP153 phenylalanine-glycine motifs engage a common binding pocket within the HIV-1 capsid protein to mediate lentiviral infectivity. Matreyek KA, Yücel SS, Li X, Engelman A. PLoS Pathog. 9 e1003693 (2013)
  15. Solution structure of the capsid protein from the human T-cell leukemia virus type-I. Khorasanizadeh S, Campos-Olivas R, Summers MF. J. Mol. Biol. 291 491-505 (1999)
  16. Structure and self-association of the Rous sarcoma virus capsid protein. Kingston RL, Fitzon-Ostendorp T, Eisenmesser EZ, Schatz GW, Vogt VM, Post CB, Rossmann MG. Structure 8 617-628 (2000)
  17. Requirements for capsid-binding and an effector function in TRIMCyp-mediated restriction of HIV-1. Diaz-Griffero F, Vandegraaff N, Li Y, McGee-Estrada K, Stremlau M, Welikala S, Si Z, Engelman A, Sodroski J. Virology 351 404-419 (2006)
  18. Domain-swapped dimerization of the HIV-1 capsid C-terminal domain. Ivanov D, Tsodikov OV, Kasanov J, Ellenberger T, Wagner G, Collins T. Proc. Natl. Acad. Sci. U.S.A. 104 4353-4358 (2007)
  19. The retroviral capsid domain dictates virion size, morphology, and coassembly of gag into virus-like particles. Ako-Adjei D, Johnson MC, Vogt VM. J. Virol. 79 13463-13472 (2005)
  20. HIV-1 maturation inhibitor bevirimat stabilizes the immature Gag lattice. Keller PW, Adamson CS, Heymann JB, Freed EO, Steven AC. J. Virol. 85 1420-1428 (2011)
  21. Mammalian SCAN domain dimer is a domain-swapped homolog of the HIV capsid C-terminal domain. Ivanov D, Stone JR, Maki JL, Collins T, Wagner G. Mol. Cell 17 137-143 (2005)
  22. Retrovirus capsid protein assembly arrangements. Mayo K, Huseby D, McDermott J, Arvidson B, Finlay L, Barklis E. J. Mol. Biol. 325 225-237 (2003)
  23. Three-dimensional structure of the M-MuLV CA protein on a lipid monolayer: a general model for retroviral capsid assembly. Ganser BK, Cheng A, Sundquist WI, Yeager M. EMBO J. 22 2886-2892 (2003)
  24. Nucleic acid binding-induced Gag dimerization in the assembly of Rous sarcoma virus particles in vitro. Ma YM, Vogt VM. J. Virol. 78 52-60 (2004)
  25. Disulfide bond stabilization of the hexameric capsomer of human immunodeficiency virus. Pornillos O, Ganser-Pornillos BK, Banumathi S, Hua Y, Yeager M. J. Mol. Biol. 401 985-995 (2010)
  26. Second-site suppressors of Rous sarcoma virus Ca mutations: evidence for interdomain interactions. Bowzard JB, Wills JW, Craven RC. J. Virol. 75 6850-6856 (2001)
  27. Identification of the regions of Fv1 necessary for murine leukemia virus restriction. Bishop KN, Bock M, Towers G, Stoye JP. J. Virol. 75 5182-5188 (2001)
  28. Retroviral capsid determinants of Fv1 NB and NR tropism. Stevens A, Bock M, Ellis S, LeTissier P, Bishop KN, Yap MW, Taylor W, Stoye JP. J. Virol. 78 9592-9598 (2004)
  29. Structural analysis of the N-terminal domain of the human T-cell leukemia virus capsid protein. Cornilescu CC, Bouamr F, Yao X, Carter C, Tjandra N. J. Mol. Biol. 306 783-797 (2001)
  30. Role of the Rous sarcoma virus p10 domain in shape determination of gag virus-like particles assembled in vitro and within Escherichia coli. Joshi SM, Vogt VM. J. Virol. 74 10260-10268 (2000)
  31. Unclosed HIV-1 capsids suggest a curled sheet model of assembly. Yu Z, Dobro MJ, Woodward CL, Levandovsky A, Danielson CM, Sandrin V, Shi J, Aiken C, Zandi R, Hope TJ, Jensen GJ. J. Mol. Biol. 425 112-123 (2013)
  32. Viral DNA synthesis defects in assembly-competent Rous sarcoma virus CA mutants. Cairns TM, Craven RC. J. Virol. 75 242-250 (2001)
  33. Dimeric rous sarcoma virus capsid protein structure relevant to immature Gag assembly. Nandhagopal N, Simpson AA, Johnson MC, Francisco AB, Schatz GW, Rossmann MG, Vogt VM. J. Mol. Biol. 335 275-282 (2004)
  34. The organization of mature Rous sarcoma virus as studied by cryoelectron microscopy. Kingston RL, Olson NH, Vogt VM. J. Struct. Biol. 136 67-80 (2001)
  35. Critical role of conserved hydrophobic residues within the major homology region in mature retroviral capsid assembly. Purdy JG, Flanagan JM, Ropson IJ, Rennoll-Bankert KE, Craven RC. J. Virol. 82 5951-5961 (2008)
  36. A molecular switch required for retrovirus assembly participates in the hexagonal immature lattice. Phillips JM, Murray PS, Murray D, Vogt VM. EMBO J. 27 1411-1420 (2008)
  37. Ty3 capsid mutations reveal early and late functions of the amino-terminal domain. Larsen LS, Zhang M, Beliakova-Bethell N, Bilanchone V, Lamsa A, Nagashima K, Najdi R, Kosaka K, Kovacevic V, Cheng J, Baldi P, Hatfield GW, Sandmeyer S. J. Virol. 81 6957-6972 (2007)
  38. NMR structure of the N-terminal domain of capsid protein from the mason-pfizer monkey virus. Macek P, Chmelík J, Krízová I, Kaderávek P, Padrta P, Zídek L, Wildová M, Hadravová R, Chaloupková R, Pichová I, Ruml T, Rumlová M, Sklenár V. J. Mol. Biol. 392 100-114 (2009)
  39. Specific in vitro cleavage of Mason-Pfizer monkey virus capsid protein: evidence for a potential role of retroviral protease in early stages of infection. Rumlová M, Ruml T, Pohl J, Pichová I. Virology 310 310-318 (2003)
  40. Multiple sites in the N-terminal half of simian immunodeficiency virus capsid protein contribute to evasion from rhesus monkey TRIM5α-mediated restriction. Kono K, Song H, Yokoyama M, Sato H, Shioda T, Nakayama EE. Retrovirology 7 72 (2010)
  41. Reverse Transcriptase and Cellular Factors: Regulators of HIV-1 Reverse Transcription. Warren K, Warrilow D, Meredith L, Harrich D. Viruses 1 873-894 (2009)
  42. Second-site compensatory mutations of HIV-1 capsid mutations. Noviello CM, López CS, Kukull B, McNett H, Still A, Eccles J, Sloan R, Barklis E. J. Virol. 85 4730-4738 (2011)
  43. A unique spumavirus Gag N-terminal domain with functional properties of orthoretroviral matrix and capsid. Goldstone DC, Flower TG, Ball NJ, Sanz-Ramos M, Yap MW, Ogrodowicz RW, Stanke N, Reh J, Lindemann D, Stoye JP, Taylor IA. PLoS Pathog. 9 e1003376 (2013)
  44. Availability of a diversely avid CD8+ T cell repertoire specific for the subdominant HLA-A2-restricted HIV-1 Gag p2419-27 epitope. Schaubert KL, Price DA, Frahm N, Li J, Ng HL, Joseph A, Paul E, Majumder B, Ayyavoo V, Gostick E, Adams S, Marincola FM, Sewell AK, Altfeld M, Brenchley JM, Douek DC, Yang OO, Brander C, Goldstein H, Kan-Mitchell J. J. Immunol. 178 7756-7766 (2007)
  45. Structure of the capsid amino-terminal domain from the betaretrovirus, Jaagsiekte sheep retrovirus. Mortuza GB, Goldstone DC, Pashley C, Haire LF, Palmarini M, Taylor WR, Stoye JP, Taylor IA. J. Mol. Biol. 386 1179-1192 (2009)
  46. Comparison of classical and affinity purification techniques of Mason-Pfizer monkey virus capsid protein: the alteration of the product by an affinity tag. Rumlová M, Benedíková J, Cubínková R, Pichová I, Ruml T. Protein Expr. Purif. 23 75-83 (2001)
  47. Primate TRIM5 proteins form hexagonal nets on HIV-1 capsids. Li YL, Chandrasekaran V, Carter SD, Woodward CL, Christensen DE, Dryden KA, Pornillos O, Yeager M, Ganser-Pornillos BK, Jensen GJ, Sundquist WI. Elife 5 (2016)
  48. The NH2-terminal domain of the human T-cell leukemia virus type 1 capsid protein is involved in particle formation. Rayne F, Bouamr F, Lalanne J, Mamoun RZ. J. Virol. 75 5277-5287 (2001)
  49. Phylogenetic analysis of small ruminant lentiviruses from Southern Brazil. Ravazzolo AP, Reischak D, Peterhans E, Zanoni R. Virus Res. 79 117-123 (2001)
  50. Three-dimensional organization of retroviral capsid proteins on a lipid monolayer. McDermott J, Mayo K, Barklis E. J. Mol. Biol. 302 121-133 (2000)
  51. Mutational analysis of the N-terminal domain of Moloney murine leukemia virus capsid protein. Auerbach MR, Brown KR, Singh IR. J. Virol. 81 12337-12347 (2007)
  52. Retroviral capsid assembly: a role for the CA dimer in initiation. Purdy JG, Flanagan JM, Ropson IJ, Craven RC. J. Mol. Biol. 389 438-451 (2009)
  53. Consensus structural models for the amino terminal domain of the retrovirus restriction gene Fv1 and the murine leukaemia virus capsid proteins. Taylor WR, Stoye JP. BMC Struct. Biol. 4 1 (2004)
  54. Hexagonal organization of Moloney murine leukemia virus capsid proteins. Mayo K, McDermott J, Barklis E. Virology 298 30-38 (2002)
  55. Important role for the CA-NC spacer region in the assembly of bovine immunodeficiency virus Gag protein. Guo X, Hu J, Whitney JB, Russell RS, Liang C. J. Virol. 78 551-560 (2004)
  56. In vivo homodimerisation of HTLV-1 Gag and MA gives clues to the retroviral capsid and TM envelope protein arrangement. Rayne F, Kajava AV, Lalanne J, Mamoun RZ. J. Mol. Biol. 343 903-916 (2004)
  57. The MHC-haplotype influences primary, but not memory, immune responses to an immunodominant peptide containing T- and B-cell epitopes of the caprine arthritis encephalitis virus Gag protein. Fluri A, Nenci C, Zahno ML, Vogt HR, Charan S, Busato A, Pancino G, Peterhans E, Obexer-Ruff G, Bertoni G. Vaccine 24 597-606 (2006)
  58. Design of in vitro symmetric complexes and analysis by hybrid methods reveal mechanisms of HIV capsid assembly. Yeager M. J. Mol. Biol. 410 534-552 (2011)
  59. Cooperative role of the MHR and the CA dimerization helix in the maturation of the functional retrovirus capsid. Lokhandwala PM, Nguyen TL, Bowzard JB, Craven RC. Virology 376 191-198 (2008)
  60. Crosslink analysis of N-terminal, C-terminal, and N/B determining regions of the Moloney murine leukemia virus capsid protein. McDermott J, Karanjia S, Love Z, Barklis E. Virology 269 190-200 (2000)
  61. Homology-based identification of capsid determinants that protect HIV1 from human TRIM5α restriction. Maillard PV, Zoete V, Michielin O, Trono D. J. Biol. Chem. 286 8128-8140 (2011)
  62. The effect of point mutations within the N-terminal domain of Mason-Pfizer monkey virus capsid protein on virus core assembly and infectivity. Wildová M, Hadravová R, Stokrová J, Krízová I, Ruml T, Hunter E, Pichová I, Rumlová M. Virology 380 157-163 (2008)
  63. Structural consequences of cyclophilin A binding on maturational refolding in human immunodeficiency virus type 1 capsid protein. Dietrich L, Ehrlich LS, LaGrassa TJ, Ebbets-Reed D, Carter C. J. Virol. 75 4721-4733 (2001)
  64. Analysis of the retrovirus capsid interdomain linker region. Arvidson B, Seeds J, Webb M, Finlay L, Barklis E. Virology 308 166-177 (2003)
  65. Contributions of Charged Residues in Structurally Dynamic Capsid Surface Loops to Rous Sarcoma Virus Assembly. Heyrana KJ, Goh BC, Perilla JR, Nguyen TN, England MR, Bewley MC, Schulten K, Craven RC. J. Virol. 90 5700-5714 (2016)
  66. Elicitation of immunity to HIV type 1 Gag is determined by Gag structure. Young KR, Ross TM. AIDS Res. Hum. Retroviruses 22 99-108 (2006)
  67. Evolution of feline immunodeficiency virus Gag proteins. Burkala E, Poss M. Virus Genes 35 251-264 (2007)
  68. Structure of a Spumaretrovirus Gag Central Domain Reveals an Ancient Retroviral Capsid. Ball NJ, Nicastro G, Dutta M, Pollard DJ, Goldstone DC, Sanz-Ramos M, Ramos A, Müllers E, Stirnnagel K, Stanke N, Lindemann D, Stoye JP, Taylor WR, Rosenthal PB, Taylor IA. PLoS Pathog. 12 e1005981 (2016)
  69. Systematic epitope analysis of the p26 EIAV core protein. Soutullo A, Santi MN, Perin JC, Beltramini LM, Borel IM, Frank R, Tonarelli GG. J. Mol. Recognit. 20 227-237 (2007)
  70. Circular dichroism and fluorescence spectroscopic properties of the major core protein of feline immunodeficiency virus and its tryptophan mutants. Assignment of the individual contribution of the aromatic sidechains. Yélamos B, Núñez E, Gómez-Gutiérrez J, Datta M, Pacheco B, Peterson DL, Gavilanes F. Eur. J. Biochem. 266 1081-1089 (1999)
  71. Identification of Capsid/Coat Related Protein Folds and Their Utility for Virus Classification. Nasir A, Caetano-Anollés G. Front Microbiol 8 380 (2017)
  72. Identification and characterization of a common B-cell epitope on EIAV capsid proteins. Hu Z, Chang H, Chu X, Li S, Wang M, Wang X. Appl. Microbiol. Biotechnol. 100 10531-10542 (2016)
  73. 1H, 13C, and 15N resonance assignment of the N-terminal domain of Mason-Pfizer monkey virus capsid protein, CA 1-140. Macek P, Zídek L, Rumlová M, Pichová I, Sklenár V. Biomol NMR Assign 2 43-45 (2008)
  74. Production of Equine Infectious Anemia Virus (EIAV) antigen in Pichia pastoris. de Arruda Coutinho LC, de Jesus AL, de Paiva Fontes KF, Coimbra EC, Mariz FC, de Freitas AC, de Cássia Carvalho Maia R, de Castro RS. J. Virol. Methods 191 95-100 (2013)
  75. High Genomic Variability in Equine Infectious Anemia Virus Obtained from Naturally Infected Horses in Pantanal, Brazil: An Endemic Region Case. Malossi CD, Fioratti EG, Cardoso JF, Magro AJ, Kroon EG, Aguiar DM, Borges AMCM, Nogueira MF, Ullmann LS, Araujo JP. Viruses 12 (2020)
  76. Conserved cysteines in Mason-Pfizer monkey virus capsid protein are essential for infectious mature particle formation. Píchalová R, Füzik T, Vokatá B, Rumlová M, Llano M, Dostálková A, Křížová I, Ruml T, Ulbrich P. Virology 521 108-117 (2018)
  77. Identification of 2-(4-N,N-Dimethylaminophenyl)-5-methyl-1-phenethyl-1H-benzimidazole targeting HIV-1 CA capsid protein and inhibiting HIV-1 replication in cellulo. Alvarez G, van Pul L, Robert X, Artía Z, van Nuenen AC, Long M, Sierra N, Porcal W, Kootstra NA, Guillon C. BMC Pharmacol Toxicol 23 43 (2022)
  78. Long-range effects of tag sequence on marginally stabilized structure in HIV-1 p24 capsid protein monitored using NMR. Okazaki H, Kaneko C, Hirahara M, Watanabe S, Tochio N, Kigawa T, Nishimura C. Biochim. Biophys. Acta 1844 1638-1647 (2014)
  79. Symmetry-based self-assembled nanotubes constructed using native protein structures: the key role of flexible linkers. Buch I, Tsai CJ, Wolfson HJ, Nussinov R. Protein Pept Lett 18 362-372 (2011)
  80. The Conserved Tyr176/Leu177 Motif in the α-Helix 9 of the Feline Immunodeficiency Virus Capsid Protein Is Critical for Gag Particle Assembly. Ovejero CA, González SA, Affranchino JL. Viruses 11 (2019)


Related citations provided by authors (1)

  1. Cloning, expression, purification, and characterization of the major core protein (p26) from equine infectious anemia virus.. Birkett AJ, Yélamos B, Rodríguez-Crespo I, Gavilanes F, Peterson DL Biochim Biophys Acta 1339 62-72 (1997)