scholarly journals Topology and quaternary structure of pro-sucrase/isomaltase and final-form sucrase/isomaltase

1986 ◽  
Vol 237 (2) ◽  
pp. 455-461 ◽  
Author(s):  
G M Cowell ◽  
J Tranum-Jensen ◽  
H Sjöström ◽  
O Norén
Keyword(s):  
Electron Microscopy ◽  
Quaternary Structure ◽  
Functional Organization ◽  
Enzyme Complex ◽  
Single Chain ◽  
Pancreatic Duct Ligation ◽  
Duct Ligation ◽  
Catalytically Active ◽  
Identical Series ◽  
Dimeric Model

Pig sucrase/isomaltase (EC 3.2.1.48/10) was purified from intestinal microvillar vesicles prepared from animals with and without pancreatic-duct ligation to obtain the single-chain pro form and the proteolytically cleaved final form respectively. The purified enzymes were re-incorporated into phosphatidylcholine vesicles and analysed by electron microscopy after negative staining. The two forms of the enzyme were observed as identical series of characteristic projected views that could be unified in a single dimeric model, containing two sucrase and two isomaltase units. This shows a homodimeric functional organization similar to that of other microvillar hydrolases. The bulk of the dimer was separated from the membrane by a maximal gap of 3.5 nm, representing a junctional segment connecting the intramembrane section of the anchor to the catalytically active domain of sucrase/isomaltase. The enzyme complex protrudes from the membrane for a distance of up to 17 nm. From charge-shift immunoelectrophoresic studies of hydrophilic prosucrase/isomaltase and from electron microscopy of reconstituted pro-sucrase/isomaltase, there was no evidence to suggest the presence of anchoring sequences between the sucrase and isomaltase subunits.

Quaternary structure of Limulus polyphemus hemocyanin

1978 ◽  
Vol 36 (2) ◽  
pp. 176-177
Author(s):  
T. Wichertjes ◽  
E.J. Kwak ◽  
E.F.J. Van Bruggen
Keyword(s):  
Electron Microscopy ◽  
Functional Properties ◽  
Horseshoe Crab ◽  
Temperature Jump ◽  
Quaternary Structure ◽  
Crystallographic Analysis ◽  
Limulus Polyphemus ◽  
Oxygen Binding ◽  
X Ray ◽  
Intact Molecule

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

Characterization of Tamm-Horsfall Urinary Glycoprotein

1973 ◽  
Vol 31 ◽  
pp. 420-421
Author(s):  
John P. Robinson ◽  
J. David Puett
Keyword(s):  
Electron Microscopy ◽  
Circular Dichroism ◽  
Secondary Structure ◽  
Quaternary Structure ◽  
Normal Adult ◽  
Morphological Properties ◽  
Adult Males ◽  
Circular Dichroïsm ◽  
Urinary Glycoprotein

Much work has been reported on the chemical, physical and morphological properties of urinary Tamm-Horsfall glycoprotein (THG). Although it was once reported that cystic fibrotic (CF) individuals had a defective THG, more recent data indicate that THG and CF-THG are similar if not identical.No studies on the conformational aspects have been reported on this glycoprotein using circular dichroism (CD). We examined the secondary structure of THG and derivatives under various conditions and have correlated these results with quaternary structure using electron microscopy.THG was prepared from normal adult males and CF-THG from a 16-year old CF female by the method of Tamm and Horsfall. CF female by the method of Tamm and Horsfall.

Structural modifications of intercellular junctions.

1978 ◽  
Vol 36 (2) ◽  
pp. 330-331
Author(s):  
J. Metz ◽  
M. Merlo ◽  
W. G. Forssmann
Keyword(s):  
Gap Junctions ◽  
Intercellular Junctions ◽  
Cell Isolation ◽  
Extrahepatic Cholestasis ◽  
Structural Modifications ◽  
Pancreatic Duct Ligation ◽  
Pancreatic Cells ◽  
Duct Ligation ◽  
Thin Sectioning ◽  
And Function

Structure and function of intercellular junctions were studied under the electronmicroscope using conventional thin sectioning and freeze-etch replicas. Alterations of tight and gap junctions were analyzed 1. of exocrine pancreatic cells under cell isolation conditions and pancreatic duct ligation and 2. of hepatocytes during extrahepatic cholestasis.During the different steps of cell isolation of exocrine pancreatic cells, gradual changes of tight and gap junctions were observed. Tight junctions, which formed belt-like structures around the apex of control acinar cells in situ, subsequently diminished, became interrupted and were concentrated into macular areas (Fig. 1). Aggregations of membrane associated particles, which looked similar to gap junctions, were intermixed within tight junctional areas (Fig. 1). These structures continously disappeared in the last stages of the isolation procedure. The intercellular junctions were finally separated without destroying the integrity of the cell membrane, which was confirmed with porcion yellow, lanthanum chloride and horse radish peroxidase.

Electron Microscopy and image reconstruction reveal the structural basis for spectrin's elastic properties

1992 ◽  
Vol 50 (1) ◽  
pp. 510-511
Author(s):  
Amy M. McGough ◽  
Robert Josephs
Keyword(s):  
Electron Microscopy ◽  
Elastic Properties ◽  
Conformational Changes ◽  
Quaternary Structure ◽  
Three Dimensional ◽  
Membrane Skeleton ◽  
Projection Algorithm ◽  
Structural Basis ◽  
Iterative Approximation ◽  
Membrane Skeletons

The remarkable deformability of the erythrocyte derives in large part from the elastic properties of spectrin, the major component of the membrane skeleton. It is generally accepted that spectrin's elasticity arises from marked conformational changes which include variations in its overall length (1). In this work the structure of spectrin in partially expanded membrane skeletons was studied by electron microscopy to determine the molecular basis for spectrin's elastic properties. Spectrin molecules were analysed with respect to three features: length, conformation, and quaternary structure. The results of these studies lead to a model of how spectrin mediates the elastic deformation of the erythrocyte.Membrane skeletons were isolated from erythrocyte membrane ghosts, negatively stained, and examined by transmission electron microscopy (2). Particle lengths and end-to-end distances were measured from enlarged prints using the computer program MACMEASURE. Spectrin conformation (straightness) was assessed by calculating the particles’ correlation length by iterative approximation (3). Digitised spectrin images were correlation averaged or Fourier filtered to improve their signal-to-noise ratios. Three-dimensional reconstructions were performed using a suite of programs which were based on the filtered back-projection algorithm and executed on a cluster of Microvax 3200 workstations (4).

scholarly journals Publisher Correction: Pancreatic duct ligation reduces premalignant pancreatic lesions in a Kras model of pancreatic adenocarcinoma in mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marta Cáceres ◽  
Rita Quesada ◽  
Mar Iglesias ◽  
Francisco X. Real ◽  
Maria Villamonte ◽  
...  
Keyword(s):  
Pancreatic Duct ◽  
Pancreatic Adenocarcinoma ◽  
Pancreatic Duct Ligation ◽  
Duct Ligation

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

scholarly journals Somatostatin levels and binding in duodenal mucosa of rabbits with ligation of the pancreatic duct

1988 ◽  
Vol 118 (2) ◽  
pp. 227-232 ◽  
Author(s):  
L. G. Guijarro ◽  
E. Arilla
Keyword(s):  
Pancreatic Duct ◽  
Binding Sites ◽  
Exocrine Pancreas ◽  
Duodenal Mucosa ◽  
Physiological Significance ◽  
Scatchard Analysis ◽  
Pancreatic Duct Ligation ◽  
Parallel Increase ◽  
Duct Ligation ◽  
Number Of Binding Sites

ABSTRACT Atrophy of the exocrine pancreas was induced in rabbits by pancreatic duct ligation. Somatostatin concentration and binding in cytosol from rabbit duodenal mucosa were studied after 6 and 14 weeks of pancreatic duct ligation. Somatostatin-like immunoreactivity was significantly increased in the duodenal mucosa in both periods. Scatchard analysis showed a parallel increase in the number of binding sites rather than a change in their affinity. The physiological significance of these findings remains to be clarified. J. Endocr. (1988) 118, 227–232

Apoptosis associated gene expressions in pancreas after pancreatic duct ligation in rats

2001 ◽  
Vol 120 (5) ◽  
pp. A720
Author(s):  
Hong Sik Lee ◽  
Chang Duck Kim ◽  
Byung Won Hur ◽  
Chang Don Kang ◽  
Hoon Jai Chun ◽  
...  
Keyword(s):  
Pancreatic Duct ◽  
Gene Expressions ◽  
Pancreatic Duct Ligation ◽  
Duct Ligation

scholarly journals Pancreatic duct ligation reduces premalignant pancreatic lesions in a Kras model of pancreatic adenocarcinoma in mice

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marta Cáceres ◽  
Rita Quesada ◽  
Mar Iglesias ◽  
Francisco X. Real ◽  
Maria Villamonte ◽  
...  
Keyword(s):  
Pancreatic Duct ◽  
Premalignant Lesions ◽  
Ductal Adenocarcinoma ◽  
High Grade ◽  
Histological Changes ◽  
Pancreatic Duct Ligation ◽  
Duct Ligation ◽  
Risk Patients ◽  
Flat Lesions ◽  
Over Time

Abstract Pancreatic duct ligation (PDL) in the murine model has been described as an exocrine pancreatic atrophy-inducing procedure. However, its influence has scarcely been described on premalignant lesions. This study describes the histological changes of premalignant lesions and the gene expression in a well-defined model of pancreatic ductal adenocarcinoma by PDL. Selective ligation of the splenic lobe of the pancreas was performed in Ptf1a-Cre(+/ki); K-ras LSLG12Vgeo(+/ki) mice (PDL-Kras mice). Three experimental groups were evaluated: PDL group, controls and shams. The presence and number of premalignant lesions (PanIN 1–3 and Atypical Flat Lesions—AFL) in proximal (PP) and distal (DP) pancreas were studied for each group over time. Microarray analysis was performed to find differentially expressed genes (DEG) between PP and PD. Clinical human specimens after pancreaticoduodenectomy with ductal occlusion were also evaluated. PDL-Kras mice showed an intense pattern of atrophy in DP which was shrunk to a minimal portion of tissue. Mice in control and sham groups had a 7 and 10-time increase respectively of risk of high-grade PanIN 2 and 3 and AFL in their DP than PDL-Kras mice. Furthermore, PDL-Kras mice had significantly less PanIN 1 and 2 and AFL lesions in DP compared to PP. We identified 38 DEGs comparing PP and PD. Among them, several mapped to protein secretion and digestion while others such as Nupr1 have been previously associated with PanIN and PDAC. PDL in Ptf1a-Cre(+/ki); K-ras LSLG12Vgeo(+/ki) mice induces a decrease in the presence of premalignant lesions in the ligated DP. This could be a potential line of research of interest in some cancerous risk patients.

p53-Dependent acinar cell apoptosis triggers epithelial proliferation in duct-ligated murine pancreas

2000 ◽  
Vol 279 (4) ◽  
pp. G827-G836 ◽  
Author(s):  
Charles R. Scoggins ◽  
Ingrid M. Meszoely ◽  
Michihiko Wada ◽  
Anna L. Means ◽  
Liying Yang ◽  
...  
Keyword(s):  
Acinar Cell ◽  
Cell Apoptosis ◽  
Target Genes ◽  
P53 Protein ◽  
Acinar Cells ◽  
Epithelial Proliferation ◽  
Pancreatic Duct Ligation ◽  
Duct Ligation ◽  
The Relationship ◽  
P53 Target Genes

The mechanisms linking acinar cell apoptosis and ductal epithelial proliferation remain unknown. To determine the relationship between these events, pancreatic duct ligation (PDL) was performed on p53(+/+) and p53(−/−) mice. In mice bearing a wild-type p53 allele, PDL resulted in upregulation of p53 protein in both acinar cells and proliferating duct-like epithelium. In contrast, upregulation of Bcl-2 occurred only in duct-like epithelium. Both p21WAF1/CIP1 and Bax were also upregulated in duct-ligated lobes. After PDL in p53(+/+) mice, acinar cells underwent widespread apoptosis, while duct-like epithelium underwent proliferative expansion. In the absence of p53, upregulation of p53 target genes and acinar cell apoptosis did not occur. The absence of acinar cell apoptosis in p53(−/−) mice also eliminated the proliferative response to duct ligation. These data demonstrate that PDL-induced acinar cell apoptosis is a p53-dependent event and suggest a direct link between acinar cell apoptosis and proliferation of duct-like epithelium in duct-ligated pancreas.

Sign in / Sign up

Export Citation Format

Share Document