• BMB Reports
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• 제31권3호
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• pp.221-226
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• 1998

Phosphorylation of phytochrome may play important functional roles to control plant photomorphogenesis. Many attempts have failed to identify the protein kinase that phosphorylates phytochrome in vivo. It has been reported that a polycation-stimulated protein kinase activity was associated with the purified phytochrome. However, it is not known if the kinase activity is an intrinsic property of phytochrome or whether it comes from a contaminant of the purified phytochrome. In the present study, three protein kinases that phosphorylate phytochrome have been identified from etiolated oat seedlings. A polycationstimulated protein kinase that had very similar enzymatic properties with that associated with the purified phytochrome was identified in the cytosolic extract. It phosphorylated several contaminant proteins in the kinase preparation as well as phytochrome and had a broad substrate specificity. A CK II-type protein kinase phosphorylated phytochrome and the exogenously added casein. It is likely that this kinase may not be a feasible candidate for the kinase phosphorylating phytochrome in vivo since the content of the kinase seemed to well exceed the content of phytochrome in the etiolated oat seedlings. Another protein kinase that had unique enzymatic properties phosphorylated phytochrome very specifically and seemed to be present in a small quantity in the etiohlted seedlings. It is expected that one of three kinases may be responsible for the phytochrome phosphorylation in vivo.

• Rapid Communication in Photoscience
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• 제2권2호
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• pp.56-59
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• 2013

Plant phytochromes, molecular light switches that regulate various aspects of plant growth and development, are known as autophosphorylating serine/threonine kinases. Although recent studies reveal that phytochrome autophosphorylation plays an important role in the regulation of phytochrome signaling through the control of phyA protein stability, the in vivo functional roles of phytochrome kinase activity in plant light signaling are largely unknown. Thus, it is necessary to investigate the detailed function of phytochrome as a protein kinase, which might include mapping of kinase domain on the phytochrome molecule, searching for substrates that could be phosphorylated by phyA, and in vivo functional analysis of the kinase activity with phytochrome mutants displaying reduced kinase activity. Our recent studies reveal that the kinase activity of phytochrome plays a positive role in plant light signaling. Therefore, we highlight the current knowledge about the functional roles of phytochrome kinase activity in the light signal transduction of plants, based on our recent results.

• Applied Biological Chemistry
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• 제32권2호
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• pp.126-131
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• 1989

암소에서 기른 귀리로부터 얻은 59 kD phytochrome의 liposome과 Cibacron Blue dye에 대한 결합성질을 규명하였다. 124 kD 및 118 kD phytochrome과는 달리 Pfr형의 59 kD phytochrome은 liposome 및 Cibacron Blue dye와 정전기적 힘으로 결합한다. 이러한 결과는 124 kD 및 118 kD phytochrome이 Pr형에서 Pfr형으로 광변환시 노출되는 소수표면이 59kD Pfr에는 존재하지 않음을 의미한다. 비교적으로 강한 소수부분이 59 kD polypeptide에 존재함이 알려져 있으므로 C-말단부위로부터 잘려져나간 55 kD tryptic domain이 l18kD 및 124kD Pfr의 소수표면 노출에 중요할 역할을 하는 것으로 믿어진다.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1994년도 94 Symposium on Plant science September 10, 1994 Ewha Womans University, Seoul, Korea 94 식물학 심포지움 환경 스트레스와 식물의 반응
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• pp.41-51
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• 1994

Tomato (Lycopersicon esculentum Mill.) has been chosen as a model species for the study of hotomorphogenesis. The aurea (au) and yellow-green-2 (yg-2) mutants which are severely photochrome deficient appear to be phytochrome chromophore mutants. Mutants modified with respect to specific members of the phytochrome gene family: the far-red light-insensitive mutant (fri, for phytochrome A) and the temporarily red light-insensitive mutant (tri, for phytochrome B1) have been identified. Mutants that exhibit an exaggerated phytochrome response are putative transduction-chain mutants affecting an amplification step in phytochrome signal transduction. These mutants are being used to understand the complexities of juvenile anthocyanin in the hypocotyl during seedling de-etiolation.

• Journal of Microbiology and Biotechnology
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• 제16권9호
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• pp.1441-1447
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• 2006

The light perception and phototransformation of phytochromes are the first process of the phytochrome-mediated light signal transduction. The chromophore ligation and its photochromism of various site-specific and deletion mutants of pea phytochrome A and bacterial phytochrome-like protein (Cph1) were analyzed in vitro. Serial truncation mutants from the N-terminus and C-terminus indicated that the minimal N-terminal domain for the chromophore ligation spans from the residue 78 to 399 of pea phytochrome A. Site-specific mutants indicated that several residues are critical for the chromophore ligation and/or photochromism. Histidine-324 appears to serve as an anchimeric residue for photochromism through its H-bonding function. Isoleucine-80 and arginine-383 playa critical role for the chromophore ligation and photochromism. Arginine-383 is presumably involved in the stabilization of the Pfr form of pea phytochrome A. Apparently, the amphiphilic ${\alpha}$-helix centered around the residue-391 is in the chromophore pocket and critical for the chromophore ligation.

• Journal of Photoscience
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• 제7권3호
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• pp.123-128
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• 2000

Phosphorylation of cellular proteins is a key regulatory mehanism for signal transduction pathway in living cells. Phytochrome, a red/far-red light photoreceptor in plants, is known to employ protein phosphorylation for its light signaling, although its detauked mechanism is still ambiguous. This study is intended to identify the phosphoproteins and protein kinases that are regulated by phytochrome, by employing transgenic rice seedlings that overexpress Arabidopsis phytochrome A. Red light stimulated phsophorylation of a 70 kDa protein and far-red light negated the effect. The red light induced phosphotylation of the 70 kDa protein was strongly activated by heparin and inhibited by poly-L-lysine, suggesting that the 70 kDa protein phosphorylating kinase belongs to GSK-3/SHAGGY protein kinase that has functional roles in establishing cell fate and pattern formation in Drosophila. Taken together with the fact that phytochrome controls plant development, these results may suggest that a GSK-3/SHAGGY-related protein kinase in plant(ASK) is likely to be involved in phytochrome signal transduction.

• Bulletin of the Korean Chemical Society
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• 제8권4호
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• pp.347-348
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• 1987

• 한국산림과학회지
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• 제94권4호통권161호
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• pp.236-242
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• 2005

다양한 광조건에서 식물의 생장조절에 관여하는 광수용체인 phytochrome B(PhyB) 유전자를 교잡종 포플러 수항1호에서 분리하였다. 염기서열분석 결과, PhyB cDNA는 길이가 3,456bp 이었으며 1,156개의 아미노산으로 구성된 단백질을 암호화하고 있는 것으로 나타났다. PhyB 단백질은 아미노산 수준에서 Populus balsamfera PhyB1과 98%의 높은 상동성을 나타내었다. Northern blot 분석 결과, PhyB 유전자는 광조건에서는 높은 수준으로 발현되지만, 암조건에서는 발현되지 않는 것으로 나타났다. 본 연구의 결과들을 종합하여 볼 때 PhyB는 빛에 의하여 발현이 유도되며 광수용체 역할을 하는 것으로 여겨진다.

• Journal of Photoscience
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• 제9권2호
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• pp.338-340
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• 2002

In broom sorghum, Sorghum bicolor Moench, UV causes anthocyanin synthesis having action peaks in UVA and UVB regions. We previously reported that UV induces anthocyanin synthesis through UVB photoreceptor and phytochrome activated by UV. Furthermore, UVA and UVB amplify phytochrome-induced anthocyanin synthesis (PIAS). Our action- spectroscopic research indicated that a UV -receptor for amplification of PIAS is likely to be the same or same type of UVB photoreceptor for induction of anthocyanin synthesis. UVA-amplification of PIAS can be explained by the action of a cryptic red light signal (CRS), an amplification factor for PIAS produced by a distinct phytochrome-species activated by UVA. We suggest that UVA photoreceptors are not involved in anthocyanin synthesis in the broom sorghum.

• Journal of Plant Biology
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• 제19권1호
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• pp.14-18
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• 1976

Inhibition of flowering in Lemna perpusilla 6746 by 30 mM sucrose was reversed by the addition of acetylcholine (>$10^{-4}M) supplemented with 10^{-4}M$ ascorbic acid to 1/10-strength Hunter's growth medium. The reversible effect of acetylcholine was found to be greater at early stages of flowering than in the later period. Promotive effects of both acetylcholine ($10^{-3}M) and eserine(10^{-5}M$) on flowering in the short-day plant under various photoperiodic conditions were studied. It was indicated that the application decreased length of the critical dark period for the floral induction, and it was also shown that the endogenous status of acetylcholine was involved in the floral response which had a correlation with phytochrome. Interruption of inductive dark periods by red irradiation (1min) immediately followed by far-red light (1 min) completely inhibited flowering, while the addition of acetylcholine and eserine to the medium under the same condition slightly promoted flowering, indicating possible involvement of phytochrome system in acetylcholine activity for photoperiodic sensitivity of floral response in Lemna perpusilla 6746.