scholarly journals Complex Formation of Glycosyltransferases and Their Biological Significance

2006 ◽  
Vol 18 (101) ◽  
pp. 209-230 ◽  
Author(s):  
Akira Seko
Keyword(s):  
Complex Formation ◽  
Biological Significance

scholarly journals Complex Formation between Potyvirus VPg and Translation Eukaryotic Initiation Factor 4E Correlates with Virus Infectivity

2000 ◽  
Vol 74 (17) ◽  
pp. 7730-7737 ◽  
Author(s):  
Simon Léonard ◽  
Daniel Plante ◽  
Sylvie Wittmann ◽  
Nicole Daigneault ◽  
Marc G. Fortin ◽  
...  
Keyword(s):  
Complex Formation ◽  
Aspartic Acid ◽  
Biological Significance ◽  
Virus Production ◽  
Initiation Factor ◽  
Critical Element ◽  
Virus Infectivity ◽  
Eukaryotic Initiation Factor ◽  
Interaction Domain ◽  
Initiation Of Translation

ABSTRACT The interaction between the viral protein linked to the genome (VPg) of turnip mosaic potyvirus (TuMV) and the translation eukaryotic initiation factor eIF(iso)4E of Arabidopsis thaliana has previously been reported. eIF(iso)4E binds the cap structure (m7GpppN, where N is any nucleotide) of mRNAs and has an important role in the regulation in the initiation of translation. In the present study, it was shown that not only did VPg bind eIF(iso)4E but it also interacted with the eIF4E isomer of A. thalianaas well as with eIF(iso)4E of Triticum aestivum (wheat). The interaction domain on VPg was mapped to a stretch of 35 amino acids, and substitution of an aspartic acid residue found within this region completely abolished the interaction. The cap analogue m7GTP, but not GTP, inhibited VPg-eIF(iso)4E complex formation, suggesting that VPg and cellular mRNAs compete for eIF(iso)4E binding. The biological significance of this interaction was investigated. Brassica perviridis plants were infected with a TuMV infectious cDNA (p35Tunos) and p35TuD77N, a mutant which contained the aspartic acid substitution in the VPg domain that abolished the interaction with eIF(iso)4E. After 20 days, plants bombarded with p35Tunos showed viral symptoms, while plants bombarded with p35TuD77N remained symptomless. These results suggest that VPg-eIF(iso)4E interaction is a critical element for virus production.

scholarly journals Kinetics of the inhibition of human leucocyte elastase by eglin from the leech Hirudo medicinalis

1984 ◽  
Vol 218 (3) ◽  
pp. 829-833 ◽  
Author(s):  
A Baici ◽  
U Seemüller
Keyword(s):  
Steady State ◽  
Complex Formation ◽  
Rate Constants ◽  
Biological Significance ◽  
Hirudo Medicinalis ◽  
Inhibition Mechanism ◽  
Steady State Kinetic ◽  
Leucocyte Elastase ◽  
Kinetics Of ◽  
State Kinetic

The rate constants for the inhibition of human leucocyte elastase by eglin from the leech Hirudo medicinalis were determined by using a pre-steady-state kinetic approach. kon and koff for complex-formation and dissociation were 1 × 10(6)M-1 X S-1 and 8 × 10(-4)S-1 respectively. Ki was calculated as the ratio koff/kon = 8 × 10(-10)M, the binding of eglin to elastase was reversible and the inhibition mechanism was of the fully competitive type. The mechanistic properties of the system and the biological significance of the rate constants are discussed.

Microstructural morphology of sphingolipid dispersions as investigated by freeze-fracture EM

1995 ◽  
Vol 53 ◽  
pp. 944-945
Author(s):  
Vitthal S. Kulkarni ◽  
Wayne H. Anderson ◽  
Rhoderick E. Brown
Keyword(s):  
Acyl Chain ◽  
Biological Significance ◽  
Freeze Fracture ◽  
Fatty Acyl ◽  
Fatty Acyl Moiety ◽  
Aqueous Dispersions ◽  
Head Groups ◽  
Lipid Species ◽  
Microstructural Morphology ◽  
Layer Chromatography

The biological significance of the sphingomyelins (SM) and monoglycosylated sphingolipids like galactosylceramides (GalCer) are well documented Our recent investigation showed tubular bilayers in the aqueous dispersions of N-nervonoyl GalCer [N-(24:lΔ15,cls) GalCer] (a major fatty acyl moiety of natural GalCer). To determine the influence of lipid head groups on the resulting mesophasic morphology, we investigated microstructural self-assemblies of N-nervonoyl-SM [N-(24:1 Δ15,cls) SM; the second most abundant sphingomyelin in mammalian cell membranes], 1- palmitoyl-2-nervonoyl phosphatidylcholine [PNPC] (the lipid species with the same acyl chain configuration as in N-(24: 1) GalCer) and also compared it with egg-SM by freeze-fracture EM.Procedures for synthesizing and purifying N-(24:1) GalCer, N-(24:1) SM, and PNPC have been reported . Egg-SM was purchased from Avanti Polar Lipids, Alabaster AL. All lipids were >99% pure as checked by thin layer chromatography. Lipid dispersions were prepared by hydrating dry lipid with phosphate buffer (pH 6.6) at 80-90°C (3-5 min), vigorously vortexing (1 min) and repeating this procedure for three times prior to three freeze-thaw cycles.

Ultrastructural Localization Study of Carcinoembryonic Antigen (CEA) in Gastric Cancer: Immunoelectron Microscopic Observation

1990 ◽  
Vol 48 (3) ◽  
pp. 252-253
Author(s):  
Dong Yuming ◽  
Yang Guanglin ◽  
Wu Jifeng ◽  
Chen Xiaolin
Keyword(s):  
Gastric Cancer ◽  
Intestinal Metaplasia ◽  
Cancer Cells ◽  
Microscopic Observation ◽  
Biological Significance ◽  
Ultrastructural Localization ◽  
Mucinous Carcinoma ◽  
Surface Glycoprotein ◽  
Tubular Adenocarcinoma ◽  
Pap Method

On the basis of light microscopic observation, the ultrastructural localization of CEA in gastric cancer was studied by immunoelectron microscopic technique. The distribution of CEA in gastric cancer and its biological significance and the mechanism of abnormal distribution of CEA were further discussed.Among 104 surgically resected specimens of gastric cancer with PAP method at light microscopic level, the incidence of CEA(+) was 85.58%. All of mucinous carcinoma exhibited CEA(+). In tubular adenocarcinoma the incidence of CEA(+) showed a tendency to rising with the increase of degree of differentiation. In normal epithelia and intestinal metaplasia CEA was faintly present and was found only in the luminal surface. The CEA staining patterns in cancer cells were of three types--- cytoplasmic, membranous and weak reactive type. The ultrastructural localization of CEA in 14 cases of gastric cancer was studied by immunoelectron microscopic technique.There was a little or no CEA in the microvilli of normal epithelia. In intestinal metaplasia CEA was found on the microvilli of absorptive cells and among the mucus particles of goblet cells. In gastric cancer CEA was also distributed on the lateral and basal surface or even over the entire surface of cancer cells and lost their polarity completely. Many studies had proved that the alterations in surface glycoprotein were characteristic changes of tumor cells. The antigenic determinant of CEA was glycoprotein, so the alterations of tumor-associated surface glycoprotein opened up a new way for the diagnosis of tumors.

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