• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.2
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• pp.89-94
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• 1998

Granule bound starch synthase (GBSS), also known as the '"waxy protein'", is responsible for the synthesis of amylose in the amyloplasts of cereal crops. In hexaploid wheat (Triticum aestivum L.), GBSS is involved in amylose synthesis and rolls as an important factor to determine flour quality and end-use quality in food products. Genes on three Wx loci have been found to encode GBSS in common wheats. We developed techniques for the purification and separation of GBSS in wheat. Three major GBSS isoforms, which were encoded by the genes on three loci, Wx-A1, Wx-B1, and Wx-D1 migrating differently by one dimensional SDS-po-lyacrylamide gel electrophoresis (1D SDS-PAGE), were identified. GBSS from 66 Korean hard and soft winter wheats were purified and determined for their Wx loci and four of them were identified possessing a null allele either at the Wx-A1 and Wx-B1 loci. With help of identification of three GBSS isoforms using 1D SDS-PAGE system, we are able to identify and monitor Wx gene expressions in breeding materials for developing waxy or partial waxy wheats without experiencing consecutive selecting generations.cting generations.

• Animal cells and systems
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• v.2 no.4
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• pp.489-493
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• 1998

Various heterodimers of the thyroid hormone receptor (TR) with other nuclear hormone receptors confer a wide range of transcriptional activities on thyroid hormone response elements (TREs) in the presence of the thyroid hormone ($T_3$). The present study analyzed the potential roles of retinoid X receptor (RXR) isoforms $\alpha$ and $\beta$ in $T_3$-mediated transcription on a well characterized TRE, a direct repeat of AGGTCA separated by four nucleo-tides (DR4), using electrophoretic mobility shift assays and transient transfection in CV-1 cells. We demonstrated that RXR$\alpha$ supressed liganded $TR_{\alpha}$-induced transcription while $RXR_{\beta}$ did not although both $TR_{\alpha}/RXR_{\alpha}$ and $TR_{\alpha}/RXR_{\beta}$ heterodimers were the predominant forms bound to the TRE-DR4 in the presence of $T_3$. We further demonstrated using Scatchard analysis that the two heterodimers had similar affinities for the TRE-DR4. All these observations suggest that the TRE-DR4 accomodates different types of TR/RXR heterodimers for a more finely tuned transcriptional response to $T_3$.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.303-310
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• 2011

We characterized a cytoplasmic actin gene locus in greenling Hexagrammos otakii (Scorpaeniformes). Genomic clones isolated from the greenling DNA library contained two homologous cytoplasmic actin gene copies (HObact2.1 and HObact2.2) in a tail-to-head orientation. Their gene structure is characterized by six translated exons and one non-translated exon. Exon-intron organization and the nucleotide sequences of the two actin gene isoforms are very similar. However, only the HObact2.1 isoform contains microsatellite-like, dinucleotide repeats in the 5'-flanking region (named HOms2002) and intron 1 following the non-translated exon 1 (named HOms769). One microsatellite locus (HOms769) was highly polymorphic while the other (HOms2002) was not. Based on bioinformatic analysis, different transcription factor binding motifs are related to stress and immune responses in the two actin isoforms. Semiquantitative and real-time reverse transcription-PCR assays showed that both isoform transcripts were detectable ubiquitously in all the tissues examined. However, the basal expression levels of each isoform varied across tissues. Overall, the two isoforms showed a similar, but not identical, expression pattern. Our data suggest that the cytoplasmic actin genes may be the result of a recent duplication event in the greenling genome, which has not experienced significant subfunctionalization in their housekeeping roles.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.639-644
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• 2005

The aim of this study was to investigate the effect of the myosin light chain (MLC) isoforms on the muscle fiber characteristics and meat quality traits in porcine longissimus muscle. Pale, soft, exudative (PSE) samples had a lower content of essential light chain (ELC) 1S isoforms and a higher proportion of the fiber type IIB than the reddish-pink, firm, non-exudative (RFN) samples. These compositions suggest that the PSE pork has a higher glycolytic and a lower oxidative capacity than the RFN pork. Therefore, these characteristics of PSE pork might affect the metabolic rate and meat quality traits, including protein solubility. In addition, the indicator traits of the postmortem metabolic rate were related to the ELC 1F/3F ratio ($pH_{45\;min}$: r = -0.43, P < 0.001; R-value: r = 0.53, P < 0.001). These results suggest that the MLC isoform composition can affect the postmortem metabolic rate and meat quality traits.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.3
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• pp.135-138
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• 2007

Hypertonicity imposes a great deal of stress to cells since it causes rise in cellular ionic strength, which can be reduced by the accumulation of compatible osmolytes. TonEBP plays a central role in the cellular accumulation of compatible osmolytes via transcriptional stimulation of membrane transporters and aldose reductase. Alternatively spliced forms of TonEBP mRNA have previously been reported and two of them showed different transcriptional activity. In the present study, isoform-specific antibodies were produced to confirm the translation of the spliced mRNA to protein. TonEBP was immunoprecipitated by using anti-TonEBP antibody and then immunoblotted using anti-TonEBP or isoform specific antibodies to find out the expression profile of TonEBP isoforms in basal or stimulated condition. From these results, we conclude that all TonEBP isoforms are expressed in mammalian cells and their expression patterns are not same in every cells.

• Animal cells and systems
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• v.2 no.2
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• pp.229-232
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• 1998

Lysophosphatidylcholine (LPC) has been reported to be responsible for the sustained activation of protein kinase C (PKC). As chondroqenesis is known to be regulated by PKC, this study was performed to investigate the effects of LPC on chondrogenesis of chick limb bud mesenchymes in vitro. LPC treatment of mesenchymes during micromass culture significantly enhanced chondrogenic differentiation. The most effective time of LPC on the stimulation of chondrogenesis was the first day of micromass culture. Analysis of LPC effects on the expression of PKC isoforms revealed that LPC treatment increased expression of PKCa, among the multiple PKC isoforms, in the membrane fraction on day one of culture. The stimulatory effect of LPC on chondrogenesis was abolished if PKCa was down regulated by the prolonged treatment of cells with phorbol ester. The results suqqest that LPC promotes chondrogenesis through the activation of PKCa at the early stage of chondrogenic differentiation.

• Journal of the Korean Magnetic Resonance Society
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• v.26 no.4
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• pp.46-50
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• 2022

Antifreeze proteins (AFPs) bind to the ice crystals and then are able to inhibit the freezing of body fluid at subzero temperatures. Type III AFPs are categorized into three subgroups, QAE1, QAE2, and SP isoforms, based on differences in their isoelectric points. We prepared the QAE2 (AFP11) and SP (AFP6) isoforms of the notched-fin eelpout AFP and their mutant constructs and determined their temperature gradients of amide proton chemical shifts (𝚫δ/𝚫T) using NMR. The nfeAFP11 (QAE2) has the distinct 𝚫δ/𝚫T pattern of the first 3₁₀ helix compared to the QAE1 isoforms. The nfeAFP6 (SP) has the deviated 𝚫δ/𝚫T values of many residues, indicating its backbone conformational distortion. The study suggests the distortion in the H-bonding interactions and backbone conformation that is important for TH activities.

• Molecules and Cells
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• v.46 no.1
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• pp.57-64
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• 2023

In eukaryotic cells, a key RNA processing step to generate mature mRNA is the coupled reaction for cleavage and polyadenylation (CPA) at the 3' end of individual transcripts. Many transcripts are alternatively polyadenylated (APA) to produce mRNAs with different 3' ends that may either alter protein coding sequence (CDS-APA) or create different lengths of 3'UTR (tandem-APA). As the CPA reaction is intimately associated with transcriptional termination, it has been widely assumed that APA is regulated cotranscriptionally. Isoforms terminated at different regions may have distinct RNA stability under different conditions, thus altering the ratio of APA isoforms. Such differential impacts on different isoforms have been considered as post-transcriptional APA, but strictly speaking, this can only be considered "apparent" APA, as the choice is not made during the CPA reaction. Interestingly, a recent study reveals sequential APA as a new mechanism for post-transcriptional APA. This minireview will focus on this new mechanism to provide insights into various documented regulatory paradigms.

• Journal of Life Science
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• v.18 no.10
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• pp.1348-1354
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• 2008

mi transcription factor (MITF) is important in regulating the differentiation of mast cells. In particular, MITF regulates the transcription of the mouse mast cell-specific serine protease (mMCP)-6 gene, which is generally expressed by the connective tissue-type of mast cells. In this study, we investigated alternative isoforms of MITF that regulate transcription of the mMCP-6 gene in bone marrow-derived cultured mast cells in mice. The expression of MITF isoforms was examined by RT-PCR. We observed that MITF-A, -E, -H and -Mc were expressed by mucosal-type mast cells cultured in the presence of IL-3, whereas the connective tissue-type mast cells cultured in the presence of stem cell factor (SCF) expressed MITF-A. Overexpression of MITF isoforms increased luciferase activity through the mMCP-6 promoter in NIH-3T3 cells and elevated the level of mMCP-6 expression in the MC/9 mast cell line. Moreover, mMCP-6 expression in mast cells was significantly inhibited by the depletion of MITF. The transcriptional activity and DNA binding of MITF-A was comparable to that of MITF isoforms, including MITF-E, -H, and -Mc. Our results therefore suggest that MITF-A may be an important isoform of MITF in regulating the transcription of mMCP-6 in mouse connective tissue mast cells.

• Journal of Life Science
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• v.13 no.5
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• pp.658-667
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• 2003

Antioxidative enzymes (superoxide dismutase; SOD, ascorbate peroxidase; APX, glutathione reductase; GR) play major roles in scavenging mechanism of reactive oxygen species which were involved in various stress conditions including salt. In order to investigate the relation between their growth responses (dry weight) and the changes of antioxidative enzymes activity, salt-tolerant spinach beet having 15cm of shoot length were treated with various salt levels (0, 50, 200, 1000 mM NaCl) for 24 hours. Spinach beet exhibited an increase in the activity of antioxidative enzymes by salt, the maximal activity at 200 mM NaCl and the lowest activity at 50 mM NaCl in 2 hrs. after treatments. As a result of PAGE, it has been confirmed that spinach beet contained 3 isoforms (Fe-SOD, CuZn-SOD and Mn-SOD) of SOD and main isoform was CuZn- SOD form. In case of APX, isoforms of the low molecular weight(No. 7, 8) were showed strong expression especially at 200 and 400 mM NaCl treatment. Meanwhile, GR did not show specific pattern of isoforms among the salt treatments. Especially, in case of 50 mM treatment, plant showed the lowest activity of SOD with the best growth, a low enzyme activity was induced by inactivation of the Mn-SOD. Therefore, we suggested that the decrease of SOD activity at a low salt level (50 mM NaCl) or the increase of enzyme activity at a high salt level (200 mM NaCl) may be related to expression of the Mn-SOD isoform. These antioxidative enzymes showed the increase of activity in a short time by salt addition. So, it is considered that spinach beet copes effectively with a stressful condition such as salt by operating effective antioxidative defense mechanism rapidly under high salt level.