• Applied Biological Chemistry
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• v.30 no.1
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• pp.54-59
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• 1987

Occurrence of two type brassinosteroid-like substances and less molecular weight substance than brassinosteroid were suggested in immature Vicia faba seeds extracts, which were purified using various chromatographic techniques, by Korean rice-lamina inclination test.

• Journal of Life Science
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• v.17 no.12
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• pp.1729-1733
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• 2007

Brassinolide insensitive associated receptor kinase 1(BAK1) is a critical component that play an important roles in signaling of brassinosteroid biosynthesis. Brassinosteroid-deficient and -insensitive mutants showed the characteristic of dwarf symptom. The nutrient deficient tomato showing stunt phenomenon was selected from soiless cultivation system using modified Sonneveld hydroponic solution. Twenty eight protein spots showing different expression levels compared to the control were isolated from extracts of stunted tomato leaves by 2D PAGE analyses. Significantly down-regulated 6 protein spots out of 28 protein spots were analyzed and sequenced by MALDI-TOF mass spectrometry. The protein spot having pI=4.5 and MW=24 kDa was identified as a signal protein, BAK1, which is directly related to brassinosteroid biosynthesis. In addition, five other protein spots were identified as BCK1, cystein proteinase, sulfutase, peroxidase and zinc finger factor respectively, and they were also signal proteins related to brassinosteroid biosynthesis. Furthermore, amplification of 500bp of BAK1 mRNA by RT-PCR using a primer set of peptide matched regions was inhibited conpared to that of the wild type. The results sugested that the BAK1 might be regulated at the transcription level in response to nutrition applications.

• KSBB Journal
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• v.6 no.2
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• pp.123-128
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• 1991

The production of bassinosteroid-like substances of two hybrid types of Korean rice, Jangseongbyeo, Taebackbyeo were investigated. The shoots at the maximum tillering stage were extracted and purified by solvent fractionation, silica gel adsorption chromatography Sephadex LH-20 chromatography, charcoal adsorption chromatography, Bondesil chromatography and HPLC of reverse phase, successively. Biological activities of each purification step were monitored by the rice lamina inclination test. Higher activities against the rice lamina inclination test in the each purification step showed that the shoots of two cultivars biosynthesize brassinosteroids. Two cultivars also showed a similar distribution of biological activities of endogenous brassinosteroids detected by HPLC.

• Journal of Plant Biotechnology
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• v.32 no.1
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• pp.63-71
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• 2005

A cell-free enzyme solution prepared from suspension cultured cells of Phaseolus vulgaris successfully mediated conversions of cholesterol $\to$ cholestanol and 6-deoxo-28-norteasterone $\leftrightarrow$ 6-deoxo-28-nor-3-dehydroteasterone $\leftrightarrow$ 6-deoxo-28-nortyphasterol $\to$ 6-deoxo-28-norcastasterone $\to$ 28-norcastasterone. Al-though conversion of cholestanol to 6-deoxo-28-norteasterone intermediated by 6-deoxo-28-norcathasterone was not demonstrated, this strongly suggests that a complete set of biosynthetic enzymes catalyzing reactions from cholesterol to 28-norcastasterone via 6-deoxo-28-nor type brassinosteroids is endogenously present in the cells, which demonstrates that a $C_{27}$ brassinosteroids biosynthetic pathway, namely the late C-6 oxidation for $C_{27}$ brassinosteroids, is operative in the cells. Additionally, the enzyme solution mediated conversion of 28-norcastasterone to castasterone in the presence of S-adenosyl-methionine and NADPH, providing that the $C_{27}$ brassinosteroids biosynthesis is an important route to generate castasterone in the cells. Together with our previous finding that castasterone can be biosynthesized by the same biosynthetic pathway in tomato, this study demonstrates that the $C_{27}$ brassinosteroids biosynthesis is a common alternative process to maintain endo-genous level of castasterone, an active $C_{28}$ brassinosteroid, in plants.

• Journal of Life Science
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• v.22 no.3
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• pp.428-436
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• 2012

Protein phosphorylation is a universal mechanism that regulates cellular activities. The brassinosteroid (BR) signal transduction pathway is a relay of phosphorylation and dephosphorylation cascades. It starts with the BR-induced activation of the membrane receptor kinase brassinosteroid insensitive 1 (BRI1), resulting in the dephosphorylation of transcription factors such as BZR1/BES2 and BZR2/BES1 followed by BR-induced gene expression. Brassinosteroid signal transduction research has progressed rapidly by identifying the phosphorylation/dephosphorylation site(s) of the BR-regulated kinase and phosphatase substrates with a simultaneous pursuit of mutant phenotypes. Autophosphorylation, transphosphorylation, and serine/threonine and tyrosine phosphorylation of the receptor protein kinases BRI1 and BRI1-associated kinase (BAK1) have increased the understanding of the regulatory role of those kinases during physiological and developmental processes in plants. The phosphorylation event initiated by BR is also found in the regulation of receptor-mediated endocytosis and the subsequent degradation of the receptor. However, the basic molecular links of the BR signal transduction pathway are not well understood regarding this phosphorylation/dephosphorylation event. This review summarizes the current state of BR signal transduction research to uncover the phosphorylation/dephosphorylation networks and suggests directions for future research on steroid signal transduction to gain a more comprehensive understanding of the process.

• The Korea Genome Conference
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• 2002.08a
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• pp.39.2-39.2
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• 2002

• Applied Biological Chemistry
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• v.31 no.1
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• pp.106-113
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• 1988

The rice lamina inclination test indicated the presence of brassinosteroid-like active substances in immature Vicia faba seeds. Two of these were identified as castasterone and brassinolide by GC/MS and GC/SIM, respectively. Another active principle was identified as methyl 4-chloroindole-3-acetate by GC/MS and HPLC.

• Molecules and Cells
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• v.39 no.8
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• pp.587-593
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• 2016

As sessile organisms, plants must be able to adapt to the environment. Plants respond to the environment by adjusting their growth and development, which is mediated by sophisticated signaling networks that integrate multiple environmental and endogenous signals. Recently, increasing evidence has shown that a bHLH transcription factor PIF4 plays a major role in the multiple signal integration for plant growth regulation. PIF4 is a positive regulator in cell elongation and its activity is regulated by various environmental signals, including light and temperature, and hormonal signals, including auxin, gibberellic acid and brassinosteroid, both transcriptionally and post-translationally. Moreover, recent studies have shown that the circadian clock and metabolic status regulate endogenous PIF4 level. The PIF4 transcription factor cooperatively regulates the target genes involved in cell elongation with hormone-regulated transcription factors. Therefore, PIF4 is a key integrator of multiple signaling pathways, which optimizes growth in the environment. This review will discuss our current understanding of the PIF4-mediated signaling networks that control plant growth.

• Journal of Plant Biology
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• v.38 no.3
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• pp.219-225
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• 1995

Five kinds of 4-demethylsterol were isolated from suspension cultured cells of a liverworth, Marchantia polymorpha. Four 4-demethylsterols among them were analyzed by a capillary gas chromatography-massspectrometry and 500 MHz 1H-NMR, and characterized to be avenasterol, 24-methylene-cholesterol, stigmasterol, and campesterol. And the fifth 4-demethylsterol was characterized to be sitosterol by a capillary gas chromatography-mass spectrometry. The concentration of the 4-demethylsterols in the cell decreased in order of avenasterol>stigmasterol>24-methylene-cholesterol>campesterol>sitosterol. When carbon skeleton and the oxidation state was compared with those of brassinosteroids, these 4-demethylsterols may be potent biosynthetic procusors of brassinosteroids in the cells.

• Proceedings of the Zoological Society Korea Conference
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• 2001.10a
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• pp.223.3-223
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• 2001

No Abstract, See Full Text