Dokument

Zusammenfassung:
Cryptochrome (CRY) sind UV-A/Blaulicht Photorezeptoren, die in allen Organismenreichen vorkommen und eine hohe strukturelle Ähnlichkeit zu DNA-Photolyasen haben. Sie tragen die gleichen Kofaktoren wie DNA-Photolyasen, zeigen aber mit Ausnahme der cryDASH-Familie keine DNA-Reparaturaktivität. Cryptochrome nutzen stattdessen das Lichtsignal, um um in Pflanzen deren Entwicklung zu steuern. Cryptochrom 1 (CRY1) und 2 (CRY2) aus Arabidopsis thaliana vermitteln nach Absorption des Lichtsignals über die in ihrer N-terminalen PHR (photolyase related) Domäne gebundenen Chromophore die Signalweiterleitung über ihre C-terminale Extension an downstream Interaktionspartner. Eine lichtabhängige Phosphorylierung sowie Dimerisierung scheint für beide Cryptochrome für die Signaltransduktion und ihre biologische Funktion essentiell zu sein. Während CRY1 lichtstabil ist, wird CRY2 nach Blaulichtbelichtung schnell abgebaut. Die vorliegende Arbeit beschäftigt sich mit der Charakterisierung von Arabidopsis CRY2. Insbesondere die Prozesse der Dimerisierung, der Phosphorylierung und des lichtgesteuerten Abbaus wurden näher untersucht. Cryptochrom 2 interagiert über seinen C-Terminus (CCT2) mit der C-terminalen WD-40 Domäne von COP1, einer E3-Ligase, die als Repressor der Photomorphogense in Pflanzen fungiert. Des Weiteren haben unter anderem Untersuchungen in unserer Arbeitsgruppe gezeigt, dass nur die dimere Form von CCT2 biologisch aktiv ist. Ein Ziel der vorliegenden Arbeit war es, CCT2 als Fusion mit dem Rapalog-induzierbaren FKBP(v)-Protein, sowie COP1 als Volllängen- oder verkürztes Protein, welches nur aus der C-terminalen Domäne besteht, in E. coli löslich zu exprimieren und anschließend mittels Affinitätschromatographie aufzureinigen. Mit Hilfe dieser Proteine sollte geklärt werden, ob nur die dimere Form von CCT2 mit COP1 interagiert. Hierfür waren Co-Immunopräzipitationsanalysen (Co-IP) geplant. Weiterhin sollten die gereinigten Proteine für Kokristallisationsexperimente eingesetzt werden. Die Ausbeuten an löslichem COP1, bzw. verkürzter COP1 Proteine waren gering und Versuche der Optimierung der Expression gelangen nicht. Des Weiteren zeigte sich, dass das CCT2-Fusionsprotein nach Expression in E. coli und nachfolgender Aufreinigung und Ankonzentrierung Oligomere bereits ohne Zugabe des chemischen Inducer bildet. Dennoch wurden Co-IPs durchgeführt, die aber keine Aussage darüber ermöglichten, ob CCT2 als Dimer für die Interaktion mit COP1 vorliegen muss. Aufgrund der vorgenannten Probleme war eine Kokristallisation von CCT2 mit COP1 nicht möglich. Die blaulichtabhängige Phosphorylierung und der Abbau von CRY2 in vivo wurde durch immunologische Analysen untersucht. Inbesondere wurde hierbei der Frage nachgegangen, welchen Einfluss Mitglieder der SPA-Proteinfamilie auf die Phosphorylierung und den Abbau von CRY2 haben. Die vier in Arabidopsis vorhandenen SPA Proteine fungieren zusammen mit COP1 ebenfalls als Repressoren der Photomorphogenese. Zur Beantwortung der Frage, ob SPA-Proteine am Abbau von CRY2 beteiligt sind, wurden CRY2 Gehalte in zahlreichen spa Mutanten untersucht. Weiterhin wurde eine mögliche Interaktion von SPA Proteinen mit CRY2 in vitro überprüft. Es konnte hierbei ein Einfluss der SPA Proteine auf die Stabilität von CRY2 im Blaulicht gezeigt werden, inbesondere unter niedrigen Fluenzraten. In Co-IP Analysen wurde eine direkte Interaktion von CRY2 mit SPA1 und SPA4 gezeigt. Zusammengefasst zeigen die erzielten Ergebnisse, dass SPA-Proteine am Abbau von CRY2 beteiligt sind und hierfür vermutlich eine direkte Interaktion von CRY2 mit SPA1 und SPA4 erforderlich ist. Weitere Analysen von CRY2 Proteinleveln in phyA Mutanten zeigten einen bis dahin unbekannten Einfluss von Phytochrom A auf die Stabilität von CRY2. Konsistent mit der Rolle der SPA-Proteine im Signalweg von phyA wiesen die phyA-Mutanten im niedrigen Fluenzratenbereich höhrere CRY2-Level als der Wildtyp auf. Dieser phyA Effekt wurde nur im Blaulicht, nicht aber unter Rot- und Dunkelrotlicht beobachtet. Somit kann davon ausgegangen werden, dass für den Abbau von CRY2 dessen vorherige Aktivierung durch Blaulicht zwingend erforderlich ist. Die Analyse einer phyB-Mutante zeigte hingegen keinen Unterschied zum Wildtyp. D

Bibliographie / References

1. Wang, Z.Y., and Tobin, E.M. (1998). Constitutive expression of the CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) gene disrupts circadian rhythms and suppresses its own expression. Cell 93, 1207-1217.
2. Sakamoto, K., and Briggs, W.R. (2002). Cellular and subcellular localization of phototropin 1. Plant Cell 14, 1723-1735.
3. Somers, D.E., Kim, W.Y., and Geng, R. (2004). The F-box protein ZEITLUPE confers dosage- dependent control on the circadian clock, photomorphogenesis, and flowering time. Plant Cell 16, 769-782.
4. Yu, X., Klejnot, J., Zhao, X., Shalitin, D., Maymon, M., Yang, H., Lee, J., Liu, X., Lopez, J., and Lin, C. (2007). Arabidopsis cryptochrome 2 completes its posttranslational life cycle in the nucleus. Plant Cell 19, 3146-3156.
5. Mockler, T.C., Guo, H., Yang, H., Duong, H., and Lin, C. (1999). Antagonistic actions of Arabidopsis cryptochromes and phytochrome B in the regulation of floral induction. Development 126, 2073-2082.
6. Mazzella, M.A., Cerdan, P.D., Staneloni, R.J., and Casal, J.J. (2001b). Hierarchical coupling of phytochromes and cryptochromes reconciles stability and light modulation of Arabidopsis development. Development 128, 2291-2299.
7. Yang, H.Q., Wu, Y.J., Tang, R.H., Liu, D., Liu, Y., and Cashmore, A.R. (2000). The C termini of Arabidopsis cryptochromes mediate a constitutive light response. Cell 103, 815-827.
8. Lin, C., and Shalitin, D. (2003). Cryptochrome structure and signal transduction. Annu Rev Plant Biol 54, 469-496.
9. Moller, A., Sagasser, S., Wiltschko, W., and Schierwater, B. (2004). Retinal cryptochrome in a migratory passerine bird: a possible transducer for the avian magnetic compass. Naturwissenschaften 91, 585-588.
10. Rosenfeldt, G., Viana, R.M., Mootz, H.D., von Arnim, A.G., and Batschauer, A. (2008). Chemically induced and light-independent cryptochrome photoreceptor activation. Mol Plant 1, 4-14.
11. Saijo, Y., Sullivan, J.A., Wang, H., Yang, J., Shen, Y., Rubio, V., Ma, L., Hoecker, U., and Deng, X.W. (2003). The COP1-SPA1 interaction defines a critical step in phytochrome A-mediated regulation of HY5 activity. Genes Dev 17, 2642-2647.
12. Sharrock, R.A., and Quail, P.H. (1989). Novel phytochrome sequences in Arabidopsis thaliana: structure, evolution, and differential expression of a plant regulatory photoreceptor family. Genes Dev 3, 1745-1757.
13. Mees, A., Klar, T., Gnau, P., Hennecke, U., Eker, A.P., Carell, T., and Essen, L.O. (2004). Crystal structure of a photolyase bound to a CPD-like DNA lesion after in situ repair. Science 306, 1789-1793.
14. Ni, M., Tepperman, J.M., and Quail, P.H. (1999). Binding of phytochrome B to its nuclear signalling partner PIF3 is reversibly induced by light. Nature 400, 781-784.
15. Selby, C.P., and Sancar, A. (2006). A cryptochrome/photolyase class of enzymes with single- stranded DNA-specific photolyase activity. Proc Natl Acad Sci U S A 103, 17696-17700.
16. Action spectra for phytochrome A-and B-specific photoinduction of seed germination in Arabidopsis thaliana. Proc Natl Acad Sci U S A 93, 8129-8133.
17. Ritz, T., Adem, S., and Schulten, K. (2000). A model of photoreceptor-based magnetoreception in birds. Biophys J 78 (2), 707-718.
18. Yanovsky, M.J., Mazzella, M.A., and Casal, J.J. (2000). A quadruple photoreceptor mutant still keeps track of time. Curr Biol 10, 1013-1015.
19. Shultz, R.W., Settlage, S.B., Hanley-Bowdoin, L., and Thompson, W.F. (2005). A Trichloroacetic Acid-Acetone Method Greatly Reduces Infrared Autoflurescence of Protein Extracts from Plant Tissue. Plant Molecular Biology Reports 23, 405-409.
20. Mandel, M., and Higa, A. (1970). Calcium-dependent Bacteriophage DNA Infection. J Mol Biol 53, 159-162.
21. Small, G.D., Min, B., and Lefebvre, P.A. (1995). Characterization of a Chlamydomonas reinhardtii gene encoding a protein of the DNA photolyase/blue light photoreceptor family. Plant Mol Biol 28, 443-454.
22. Yamamoto, K., Okano, T., and Fukada, Y. (2001). Chicken pineal Cry genes: light-dependent up- regulation of cCry1 and cCry2 transcripts. Neurosci Lett 313, 13-16.
23. Strayer, C., Oyama, T., Schultz, T.F., Raman, R., Somers, D.E., Mas, P., Panda, S., Kreps, J.A., and Kay, S.A. (2000). Cloning of the Arabidopsis clock gene TOC1, an autoregulatory response regulator homolog. Science 289, 768-771.
24. Suarez-Lopez, P., Wheatley, K., Robson, F., Onouchi, H., Valverde, F., and Coupland, G. (2001). CONSTANS mediates between the circadian clock and the control of flowering in Arabidopsis. Nature 410, 1116-1120.
25. Yi, C., and Deng, X.W. (2005). COP1 -from plant photomorphogenesis to mammalian tumorigenesis. Trends Cell Biol 15, 618-625.
26. Lin, C., Ahmad, M., Chan, J., and Cashmore, A.R. (1996). CRY2: a second member of the Arabidopsis cryptochrome gene family. Plant Physiol 110, 1047.
27. Ninu, L., Ahmad, M., Miarelli, C., Cashmore, A.R., and Giuliano, G. (1999). Cryptochrome 1 controls tomato development in response to blue light. Plant J 18, 551-556.
28. Senger, H. (1984). Cryptochrome, some terminological thoughts. In Blue Light Effects in Biological Systems. Edited by Senger H: Springer Verlag, Berlin; 1984 72.
29. Matsushita, T., Mochizuki, N., and Nagatani, A. (2003). Dimers of the N-terminal domain of phytochrome B are functional in the nucleus. Nature 424, 571-574.
30. Wang, H., Ma, L.G., Li, J.M., Zhao, H.Y., and Deng, X.W. (2001). Direct interaction of Arabidopsis cryptochromes with COP1 in light control development. Science 294, 154-158.
31. Martinez-Garcia, J.F., Huq, E., and Quail, P.H. (2000). Direct targeting of light signals to a promoter element-bound transcription factor. Science 288, 859-863.
32. Sancar, A., and Sancar, G.B. (1988). DNA repair enzymes. Annu Rev Biochem 57, 29-67.
33. Nelson, D.C., Lasswell, J., Rogg, L.E., Cohen, M.A., and Bartel, B. (2000). FKF1, a clock-controlled gene that regulates the transition to flowering in Arabidopsis. Cell 101, 331-340.
34. Mao, J., Zhang, Y.C., Sang, Y., Li, Q.H., and Yang, H.Q. (2005). From The Cover: A role for Arabidopsis cryptochromes and COP1 in the regulation of stomatal opening. Proc Natl Acad Sci U S A 102, 12270-12275.
35. Neff, M.M., and Chory, J. (1998). Genetic interactions between phytochrome A, phytochrome B, and cryptochrome 1 during Arabidopsis development. Plant Physiol 118, 27-35.
36. Searle, I., and Coupland, G. (2004). Induction of flowering by seasonal changes in photoperiod. EMBO J 23, 1217-1222.
37. Nagatani, A., Reed, J.W., and Chory, J. (1993). Isolation and Initial Characterization of Arabidopsis Mutants That Are Deficient in Phytochrome A. Plant Physiol. 102, 269-277.
38. Seo, H.S., Yang, J.Y., Ishikawa, M., Bolle, C., Ballesteros, M.L., and Chua, N.H. (2003). LAF1 ubiquitination by COP1 controls photomorphogenesis and is stimulated by SPA1. Nature 423, 995-999.
39. Whitelam, G.C., and Halliday, K.J. (2007). Light and Plant Developement. Blackwell Publishing Ltd. Oxford, UK.
40. Weber, S. (2005). Light-driven enzymatic catalysis of DNA repair: a review of recent biophysical studies on photolyase. Biochim Biophys Acta 1707, 1-23.
41. Schneider-Poetsch, H.A.W., Kolukisaoglu, Ü., Clapham, D.H., Hughes, J., and Lamparter, T. (1998). Non-angiosperm phytochromes and the evolution of vascular plants Physiol. Plant. 102, 612-622.
42. Sakamoto, K., and Nagatani, A. (1996). Nuclear localization activity of phytochrome B. Plant J 10, 859-868.
43. Liu, H., Yu, X., Li, K., Klejnot, J., Yang, H., Lisiero, D., and Lin, C. (2008). Photoexcited CRY2 interacts with CIB1 to regulate transcription and floral initiation in Arabidopsis. Science 322, 1535-1539.
44. Somers, D.E., Devlin, P.F., and Kay, S.A. (1998). Phytochromes and cryptochromes in the entrainment of the Arabidopsis circadian clock. Science 282, 1488-1490.
45. Nagy, F., and Schafer, E. (2002). Phytochromes control photomorphogenesis by differentially regulated, interacting signaling pathways in higher plants. Annu Rev Plant Biol 53, 329-355.
46. Ni, M., Tepperman, J.M., and Quail, P.H. (1998). PIF3, a phytochrome-interacting factor necessary for normal photoinduced signal transduction, is a novel basic helix-loop-helix protein. Cell 95, 657-667.
47. Oh, E., Kim, J., Park, E., Kim, J.I., Kang, C., and Choi, G. (2004). PIL5, a phytochrome-interacting basic helix-loop-helix protein, is a key negative regulator of seed germination in Arabidopsis thaliana. Plant Cell 16, 3045-3058.
48. Malhotra, K., Kim, S.T., Batschauer, A., Dawut, L., and Sancar, A. (1995). Putative blue-light photoreceptors from Arabidopsis thaliana and Sinapis alba with a high degree of sequence homology to DNA photolyase contain the two photolyase cofactors but lack DNA repair activity. Biochemistry 34, 6892-6899.
49. Shalitin, D., Yang, H., Mockler, T.C., Maymon, M., Guo, H., Whitelam, G.C., and Lin, C. (2002). Regulation of Arabidopsis cryptochrome 2 by blue-light-dependent phosphorylation. Nature 417, 763-767.
50. Mockler, T., Yang, H., Yu, X., Parikh, D., Cheng, Y.C., Dolan, S., and Lin, C. (2003). Regulation of photoperiodic flowering by Arabidopsis photoreceptors. Proc Natl Acad Sci U S A 100, 2140- 2145.
51. Nixdorf, M., and Hoecker, U. SPA1 and DET1 act together to control photomorphogenesis throughout plant development. Planta 231, 825-833.
52. Mullis, K.B., and Faloona, F.A. (1987). Specific synthesis of DNA in vitro via a polymerase catalyzed chain reaction. Methods in Enzymol 155:, 335-350.
53. Muller, M., and Carell, T. (2009). Structural biology of DNA photolyases and cryptochromes. Curr. Opin. Struct. Biol. 19, 277-285.
54. Sancar, A. (2003). Structure and function of DNA photolyase and cryptochrome blue-light photoreceptors. Chem Rev 103, 2203-2237.
55. Lin, C., and Todo, T. (2005). The cryptochromes. Genome Biol 6, 220.
56. Salomon, M., Christie, J.M., Knieb, E., Lempert, U., and Briggs, W.R. (2000). Photochemical and mutational analysis of the FMN-binding domains of the plant blue light receptor, phototropin. Biochemistry 39, 9401-9410.
57. Schaffer, R., Ramsay, N., Samach, A., Corden, S., Putterill, J., Carre, I.A., and Coupland, G. (1998). The late elongated hypocotyl mutation of Arabidopsis disrupts circadian rhythms and the photoperiodic control of flowering. Cell 93, 1219-1229.
58. Mas, P., Devlin, P.F., Panda, S., and Kay, S.A. (2000). Functional interaction of phytochrome B and cryptochrome 2. Nature 408, 207-211.
59. Yang, J., Lin, R., Sullivan, J., Hoecker, U., Liu, B., Xu, L., Deng, X.W., and Wang, H. (2005). Light regulates COP1-mediated degradation of HFR1, a transcription factor essential for light signaling in Arabidopsis. Plant Cell 17, 804-821.
60. Sang, Y., Li, Q.H., Rubio, V., Zhang, Y.C., Mao, J., Deng, X.W., and Yang, H.Q. (2005). N-terminal domain-mediated homodimerization is required for photoreceptor activity of Arabidopsis CRYPTOCHROME 1. Plant Cell 17, 1569-1584.
61. Matsuoka, D., and Tokutomi, S. (2005). Blue light-regulated molecular switch of Ser/Thr kinase in phototropin. Proc Natl Acad Sci U S A 102, 13337-13342.
62. Schafer, E., and Bowle, C. (2002). Phytochrome-mediated photoperception and signal transduction in higher plants. EMBO Rep 3, 1042-1048.
63. Ma, L., Li, J., Qu, L., Hager, J., Chen, Z., Zhao, H., and Deng, X.W. (2001). Light control of Arabidopsis development entails coordinated regulation of genome expression and cellular pathways. Plant Cell 13, 2589-2607.
64. Schultz, T.F., Kiyosue, T., Yanovsky, M., Wada, M., and Kay, S.A. (2001). A role for LKP2 in the circadian clock of Arabidopsis. Plant Cell 13, 2659-2670.
65. Sakai, T., Wada, T., Ishiguro, S., and Okada, K. (2000). RPT2. A signal transducer of the phototropic response in Arabidopsis. Plant Cell 12, 225-236.
66. Yamamoto, Y.Y., Matsui, M., Ang, L.H., and Deng, X.W. (1998). Role of a COP1 interactive protein in mediating light-regulated gene expression in arabidopsis. Plant Cell 10, 1083-1094.
67. Lin, C. (2002). Blue light receptors and signal transduction. Plant Cell 14 Suppl, S207-225.
68. Whitelam, G.C., Johnson, E., Peng, J., Carol, P., Anderson, M.L., Cowl, J.S., and Harberd, N.P. (1993). Phytochrome A null mutants of Arabidopsis display a wild-type phenotype in white light. Plant Cell 5, 757-768.
69. Genetic and molecular analysis of an allelic series of cop1 mutants suggests functional roles for the multiple protein domains. Plant Cell 6, 487-500.
70. McNellis, T.W., von Arnim, A.G., and Deng, X.W. (1994). Overexpression of Arabidopsis COP1 results in partial suppression of light-mediated development: evidence for a light-inactivable repressor of photomorphogenesis. Plant Cell 6, 1391-1400.
71. Neff, M.M., and Van Volkenburgh, E. (1994). Light-Stimulated Cotyledon Expansion in Arabidopsis Seedlings (The Role of Phytochrome B). Plant Physiol 104, 1027-1032.
72. Liscum, E., and Briggs, W.R. (1995). Mutations in the NPH1 locus of Arabidopsis disrupt the perception of phototropic stimuli. Plant Cell 7, 473-485.
73. Sharrock, R.A., and Clack, T. (2002). Patterns of expression and normalized levels of the five Arabidopsis phytochromes. Plant Physiol 130, 442-456.
74. Oh, E., Yamaguchi, S., Hu, J., Yusuke, J., Jung, B., Paik, I., Lee, H.S., Sun, T.P., Kamiya, Y., and Choi, G. (2007). PIL5, a phytochrome-interacting bHLH protein, regulates gibberellin responsiveness by binding directly to the GAI and RGA promoters in Arabidopsis seeds. Plant Cell 19, 1192-1208.
75. Lin, C., Yang, H., Guo, H., Mockler, T., Chen, J., and Cashmore, A.R. (1998). Enhancement of blue-light sensitivity of Arabidopsis seedlings by a blue light receptor cryptochrome 2. Proc Natl Acad Sci U S A 95, 2686-2690.
76. Rosler, J., Klein, I., and Zeidler, M. (2007). Arabidopsis fhl/fhy1 double mutant reveals a distinct cytoplasmic action of phytochrome A. Proc Natl Acad Sci U S A 104, 10737-10742.
77. Shalitin, D., Yu, X., Maymon, M., Mockler, T., and Lin, C. (2003). Blue light-dependent in vivo and in vitro phosphorylation of Arabidopsis cryptochrome 1. Plant Cell 15, 2421-2429.
78. Wu, G., and Spalding, E.P. (2007). Separate functions for nuclear and cytoplasmic cryptochrome 1 during photomorphogenesis of Arabidopsis seedlings. Proc Natl Acad Sci U S A 104, 18813- 18818.
79. Lin, R., Ding, L., Casola, C., Ripoll, D.R., Feschotte, C., and Wang, H. (2007). Transposase- derived transcription factors regulate light signaling in Arabidopsis. Science 318, 1302-1305.
80. Yamaguchi, R., Nakamura, M., Mochizuki, N., Kay, S.A., and Nagatani, A. (1999). Light-dependent translocation of a phytochrome B-GFP fusion protein to the nucleus in transgenic Arabidopsis. J Cell Biol 145, 437-445.
81. Sancar, A. (2008). Structure and function of photolyase and in vivo enzymology: 50th anniversary. J Biol Chem 283, 32153-32157.
82. Yu, X., Sayegh, R., Maymon, M., Warpeha, K., Klejnot, J., Yang, H., Huang, J., Lee, J., Kaufman, L., and Lin, C. (2009). Formation of nuclear bodies of Arabidopsis CRY2 in response to blue light is associated with its blue light-dependent degradation. Plant Cell 21, 118-130.
83. Rockwell, N.C., Su, Y.S., and Lagarias, J.C. (2006). Phytochrome structure and signaling mechanisms. Annu Rev Plant Biol 57, 837-858.
84. Shin, J., Kim, K., Kang, H., Zulfugarov, I.S., Bae, G., Lee, C.H., Lee, D., and Choi, G. (2009). Phytochromes promote seedling light responses by inhibiting four negatively-acting phytochrome-interacting factors. Proc Natl Acad Sci U S A 106, 7660-7665.
85. Ritz, T., Wiltschko, R., Hore, P.J., Rodgers, C.T., Stapput, K., Thalau, P., Timmel, C.R., and Wiltschko, W. (2009). Magnetic compass of birds is based on a molecule with optimal directional sensitivity. Biophys J 96, 3451-3457.
86. Moldt, J., Pokorny, R., Orth, C., Linne, U., Geisselbrecht, Y., Marahiel, M.A., Essen, L.O., and Batschauer, A. (2009). Photoreduction of the folate cofactor in members of the photolyase family. J Biol Chem 284, 21670-21683.
87. Matsumoto, N., Hirano, T., Iwasaki, T., and Yamamoto, N. (2003). Functional analysis and intracellular localization of rice cryptochromes. Plant Physiol 133, 1494-1503.
88. Sakai, T., Kagawa, T., Kasahara, M., Swartz, T.E., Christie, J.M., Briggs, W.R., Wada, M., and Okada, K. (2001). Arabidopsis nph1 and npl1: blue light receptors that mediate both phototropism and chloroplast relocation. Proc Natl Acad Sci U S A 98, 6969-6974.
89. Sawa, M., Nusinow, D.A., Kay, S.A., and Imaizumi, T. (2007). FKF1 and GIGANTEA complex formation is required for day-length measurement in Arabidopsis. Science 318, 261-265.
90. Renart, J., Reiser, J., and Stark, G.R. (1979). Transfer of proteins from gels to diazobenzyloxymethyl-paper and detection with antisera: a method for studying antibody specificity and antigen structure. Proc Natl Acad Sci 76, 3116-3120.
91. Matsui, M., Stoop, C.D., von Arnim, A.G., Wei, N., and Deng, X.W. (1995). Arabidopsis COP1 protein specifically interacts in vitro with a cytoskeleton-associated protein, CIP1. Proc Natl Acad Sci U S A 92, 4239-4243.
92. Sharrock, R.A., and Clack, T. (2004). Heterodimerization of type II phytochromes in Arabidopsis. Proc Natl Acad Sci U S A 101, 11500-11505.
93. Monte, E., Tepperman, J.M., Al-Sady, B., Kaczorowski, K.A., Alonso, J.M., Ecker, J.R., Li, X., Zhang, Y., and Quail, P.H. (2004). The phytochrome-interacting transcription factor, PIF3, acts early, selectively, and positively in light-induced chloroplast development. Proc Natl Acad Sci U S A 101, 16091-16098.
94. Withrow, R.B., Klein, W.H., and Elstad, V. (1957). Action Spectra of Photomorphogenic Induction and Its Photoinactivation. Plant Physiol 32, 453-462.
95. Shinomura, T., Uchida, K., and Furuya, M. (2000). Elementary processes of photoperception by phytochrome A for high-irradiance response of hypocotyl elongation in Arabidopsis. Plant Physiol 122, 147-156.
96. Stacey, M.G., Kopp, O.R., Kim, T.H., and von Arnim, A.G. (2000). Modular domain structure of Arabidopsis COP1. Reconstitution of activity by fragment complementation and mutational analysis of a nuclear localization signal in planta. Plant Physiol 124, 979-990.
97. Yang, H.Q., Tang, R.H., and Cashmore, A.R. (2001). The signaling mechanism of Arabidopsis CRY1 involves direct interaction with COP1. Plant Cell 13, 2573-2587.
98. Reed, J.W., Nagatani, A., Elich, T.D., Fagan, M., and Chory, J. (1994). Phytochrome A and Phytochrome B Have Overlapping but Distinct Functions in Arabidopsis Development. Plant Physiol 104, 1139-1149.

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