• The Korean Journal of Zoology
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• v.39 no.3
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• pp.292-298
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• 1996

Receptor-mediated endocytosis of coelomic fluid proteins (CP), yolk precursor proteins, appears to be regulated by multiple GTP-binding proteins during oogenesis of a polychaete, Pseudopotamilla occelata. Transport of 125 I-CP into the oocytes of intermediate size class, at which CP is the most actively transported, is enhanced by GTP but inhibited by GTP analogues, either GTPrS or GTP$\beta$S. The effects of GTP and GTPrS on the transport were also confirmed by tracing internalization of gold-labeled CP with transmission electron microscope. Internalization of gold-labeled CP into the yolk granules was enhanced by GTP but inhibited by GTPrS.

• BMB Reports
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• v.28 no.1
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• pp.72-78
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• 1995

Time-dependent inactivation of E. coli GTP cyclohydrolase I with a 2',3'-dialdehyde derivative of GTP (oGTP) was directed to the active site of the enzyme, and was dependent on the concentration of oGTP. The kinetics of inactivation were biphasic with a rapid reaction occurring immediately upon exposure of the enzyme to oGTP followed by a slow rate of inactivation. The $K_i$ value of oGTP for the enzyme was 0.25 mM. Inactivation was prevented by preincubation of the enzyme with GTP, the substrate of the enzyme. At 100% inactivation, 2.3 mol of [8.5'-$^3H$]oGTP were bound per each enzyme subunit, which consists of two identical polypeptides. The active site residue which reacted with the affinity label was lysine. oGTP interacted selectively with the ${\varepsilon}$-amino group of lysine in the GTP-binding site to form a morpholine-like structure which was stable without sodium borohydride treatment. However, triphosphate group was eliminated during the hydrolysis step. To identify the active site of the enzyme, [8.5'-$^3H$]oGTP-labeled enzyme was cleaved by endoproteinase Lys-C, and the $^3H$-labeled peptide was purified by HPLC. The amino acid sequence of the active site peptide was Pro-Ser-Leu-Ser-Lys, which corresponds to the aminoterminal sequence of the enzyme.

• Journal of Plant Biology
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• v.39 no.2
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• pp.85-92
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• 1996

Small GTP-binding proteins are divided into three major group: Ras, Rho and Ypt/Rab. They have the conserved regions designed G1 to G5 that are critical in GDP/GTP exchange, GTP-induced conformational change and GTP hydrolysis. We isolated and characterized genomic DNA or cDNAfragments encoding G1 to G3 domains of small GTP-binding protein Rab and Rho from several plant species using two different PCR-based cloning strategies. Seven rab DNA fragments were isolated from 4 different plants, mung-bean, tobacco, rice and pepper using two degenerate primers corresponding to the GTP-binding domain G1 and G3 in small GTP-binding proteins. The amino acid sequences among these rab DNA fragments and other known small GTP-binding proteins shows that they belong to the Ypt/Rab family. Six rho DNA fragments were isolated from 5 different plants, mung-bean, rice, Arabidopsis, Allium and Gonyaulax using the nested PCR method that involves four degenerate primers corresponding to the GTP-binding domain G1, G3 and G4. The rho DNA fragments cloned show more than 90% homology to each other. Sequence comparison between plant and other known Rho family genes suggests that they are closely related (67 to 82% amino acid identity). Sequence analysis and southern blot analysis of rab and rho in mung-bean suggest than thses genes are encoded by multigene family in mung-bean.

• BMB Reports
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• v.39 no.5
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• pp.492-501
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• 2006

Since differentiation therapy is one of the promising strategies for treatment of leukemia, universal efforts have been focused on finding new differentiating agents. In that respect, we used guanosine 5'-triphosphate (GTP) to study its effects on K562 cell line. GTP, at concentrations between 25-200 ${\mu}M$, inhibited proliferation (3-90%) and induced 5-78% increase in benzidine-positive cells after 6-days of treatments of K562 cells. Flow cytometric analyses of glycophorine A (GPA) showed that GTP can induce expression of this marker in more mature erythroid cells in a time- and dose-dependent manner. These effects of GTP were also accompanied with inhibition of DNA synthesis (measured by [$^3H$]-thymidine incorporation) and early S-phase cell cycle arrest by 96 h of exposure. In contrast, no detectable effects were observed when GTP administered to unstimulated human peripheral blood lymphocytes (PBL). However, GTP induced an increase in proliferation, DNA synthesis and viability of mitogen-stimulated PBL cells. In addition, growth inhibition and differentiating effects of GTP were also induced by its corresponding nucleotides GDP, GMP and guanosine (Guo). In heat-inactivated medium, where rapid degradation of GTP via extracellular nucleotidases is slow, the anti-proliferative and differentiating effects of all type of guanine nucleotides (except Guo) were significantly decreased. Moreover, adenosine, as an inhibitor of Guo transporter system, markedly reduced the GTP effects in K562 cells, suggesting that the extracellulr degradation of GTP or its final conversion to Guo may account for the mechanism of GTP effects. This view is further supported by the fact that GTP and Guo are both capable of impeding the effects of mycophenolic acid. In conclusion, our data will hopefully have important impact on pharmaceutical evaluation of guanine nucleotides for leukemia treatments.

• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.55-61
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• 2016

Sepiapterin, a precursor for tetrahydrobiopterin, is produced in higher mammals using guanosine triphosphate (GTP) as a biosynthetic intermediate. Four genes involved in GTP biosynthesis, namely those of guanosine monophosphate kinase (gmk), nucleoside diphosphate kinase (ndk), guanosine phosphate synthetase (guaA), and inosine-5'-monophosphate dehydrogenase (guaB), were expressed in sepiapterin-producing recombinant Escherichia coli BL21(DE3) to increase intracellular GTP concentration and to improve sepiapterin production concomitantly. Coexpression of gmk, ndk, guaA, and guaB, doubled the intracellular GTP concentration and increased the maximum sepiapterin concentration up to $126.1{\pm}19.3mg/l$ (an increase of 43% compared with control cells) in batch-cultivated recombinant E. coli.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.980-985
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• 2000

Influences of Japanese green tea powder (GTP) supplementation to commercial diet on laying performance and egg quality were studied by using 60 laying hens. The experimental diet with or without 0.6% GTP was given ad libitum to the birds during the period from 6 to 71 weeks of age. The birds started egg production from 21 wk of age regardless GTP feeding. Body weight, feed intake, egg weight tended to decrease with GTP supplementation, while egg production rate tended to increase. Haugh unit score was significantly increased with GTP, which accompanied with the increased albumen height. These were observed almost throughout the laying period over 50 wk. Gel proportion in thick albumen was decreased as storage time is prolonged, then higher values of the gel proportion were recorded in the eggs from GTP group. Thick albumen of the eggs from GTP-fed layers had more carbohydrate than that from control layers. All these indicate physical stability of thick albumen in the eggs from GTP group. Thiobarbituric acid content of egg yolk tended to remain lower in the eggs from GTP group during 5-10 days of storage at room temperature. Levels of egg yolk cholesterol and yolk lipid were significantly reduced by GTP feeding. There were no significant differences in eggshell weight, shell thickness and shell strength between the two groups. Thyroid gland and liver from hens slaughtered at 71 wk of age did not differ in weight irrespective of GTP feeding. The present results suggest that GTP could modify components of edible part of egg, leading to the characteristics favourable to consumers such as high durability of thick albumen and less cholesterol in yolk, without altering general performance of the layers throughout this year round experiment.

• Journal of Yeungnam Medical Science
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• v.10 no.2
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• pp.360-368
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• 1993

GTP binding protein (G-protein) associated with membrane and involved in signal transduction was isolated from bovine brain, and molecular weight of G protein was observed. As the results, cell membranes were homogenized from bovine brain tissues and proteins of membrane were gained using 1% cholate, and progressed the chromatography. The purification process was performed by step, DEAE-Sephacel, Ulttrogel AcA 34 and heptylamine-Sepharose column chromatography. The chromatographic fractions were confirmed by GTP binding assay and SDS-polyacrylamide gel electrophoresis. Molecular weight of $Go{\alpha}$ was revealed 39,000 dalton and $G{\beta}$ 36,000 dalton. One more step of heptylamine-Sepharose was enforced to purify the GTP binding protein. Finally I gained the GTP binding protein isolated subtype of $Go{\alpha}$ and $G{\beta}$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.10
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• pp.1263-1270
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• 2007

This study was carried out to investigate the effect of green tea product (GTP) on the risk factors of atherosclerosis in ovariectomized (OVX) rats. Sprague-Dewley female rats (10 weeks) weighing approximately $279{\pm}2g$ were divided into 4 groups: sham operated control group treated with high cholesterol diet (Sham-C), OVX control group treated with high cholesterol diet (OVX-C), OVX-G 5% group treated with high cholesterol containing 5% GTP and OVX-G 20% group treated with high cholesterol diet containing 20% GTP. Serum TG concentrations was lower in OVX-G 20% group than in the OVX-C group, whereas ratio of HDL-cholesterol to total cholesterol (%) was significantly (p<0.05) increased in the 20% GTP supplementation group than in the Sham-C and OVX-C groups. Tumor necrosis $factor-{\alpha}$ levels were significantly (p<0.05) decreased in the OVX-G 20% group. Hepatic TG levels were significantly (p<0.05) lowered in OVX-G 20% group than in the other groups. Glutathione levels and antioxidant enzyme activities including glutathione-reductase and Mn-superoxide dismutase in liver were significantly (p<0.05) higher in the OVX-G 20% group in the OVX-C group. Fecal total cholesterol concentrations were increased in the GTP supplementation groups than in the OVX-C group. From the above results, it is concluded that GTP may reduce the risk of atherosclerosis via hypolipidemic action. Therefore, it may be used to possibly improve the hyperlipemia in menopausal women.

• Journal of Nutrition and Health
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• v.31 no.1
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• pp.28-35
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• 1998

This study was done to investigate the relationship between ultrasonograph fat density (ULFD) using objective measurement and serum enzymes for testing liver function in 101 healthy adults(43 males and 58 females). Average serum enzyme activities in males and females were GOT27.111U/L and 22.46IU/L, GPT 34.06IU/L and 18.501U/L, and ${\gamma}$-GTP 37.67IU/L and 17.201U/L, respectively. Males showed significantly higher activities of GPT and ${\gamma}$-GTP than females. ULFD of the obese group (BMI$\geq$25) was significantly higher than that of the nonobese group. GOT, GPT, and ${\gamma}$-GTP tended to be high in the obese group. GPT and ${\gamma}$-GTP of the high TG group (TG$\geq$170) tended to be markedly high for males, but not for females. GPT was positively correlated with ULFD, body weight , and weight-to-height, ratio, and ${\gamma}$-GTP was positively correlated with body weight, weight-to-height ratio. BNI, and KI. ULFD and ${\gamma}$-GTP were positively correlated with serum TG. These results suggests that , among serum enzymes for testing liver function, GPT has a close relationship with ULFD using objective measurement, while GOT does not. Also , ${\gamma}$-GTP has a close relationship with parameters for obesity.

• The Korean Journal of Zoology
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• v.37 no.1
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• pp.40-48
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• 1994

세포분화에 따른 Small GTP-binding protein의 역할을 밝히기 위하여 Retinoic acid(RA)와 dibutyryl cyclic AMP(dbcAMP)로 분화를 유도한 F9 기형암종세포의 형태적인 변화와 함께 Small GTP-binding protein의 분포를 조사하였다. RA와 dbcAMP를 처리한 세포는 분화유도 5일경(초기 분화 단계)에 분명한 세포의 경계를 보이기 시작하여 7일경(분화 후기 단계)에는 거의 모든 세포가 등근 분화된 형태로 전환되었다. 이 분화과정 동안 세포막에는 많은 microvilli와 lamellopodia 같은 구조물이 나타났다. 아울러 초기 분화 단계에 많은 량의 laminin이 발현되었으며 분화 후기에 microtubule의 재분포가 관찰되었다. 세종류의 Small GTP-binding protein(25 23, 21 KD)이 F9 세포의 막성분과 세포질에서 관찰되었으며 분화가 진행됨에 따라서 세단백질 모두 증가되는 양상을 보였다 이러한 결과는 Small GTP-binding protein이 F9 세포의 분화에 특별한 기능을 가지고 있음을 시사해 주고 있다.