Dynamic changes in protein components of the tight junction during liver regeneration

2001 ◽  
Vol 305 (3) ◽  
pp. 399-409 ◽  
Author(s):  
Yasuyuki Takaki ◽  
Syu-ichi Hirai ◽  
Naoyuki Manabe ◽  
Yasushi Izumi ◽  
Tomonori Hirose ◽  
...  
2018 ◽  
Vol 9 ◽  
Author(s):  
Xinghui Wang ◽  
Yang Miao ◽  
Jun Ni ◽  
Yaxian Wang ◽  
Tianmei Qian ◽  
...  

2005 ◽  
Vol 16 (4) ◽  
pp. 1725-1734 ◽  
Author(s):  
Asma Nusrat ◽  
G. Thomas Brown ◽  
Jeffrey Tom ◽  
Alex Drake ◽  
Tam T.T. Bui ◽  
...  

Occludin is a tetraspan integral membrane protein in epithelial and endothelial tight junction (TJ) structures that is projected to have two extracellular loops. We have used peptides emulating central regions of human occludin's first and second loops, termed O-A:101–121 and O-B:210–228, respectively, to examine potential molecular interactions between these two regions of occludin and other TJ proteins. A superficial biophysical assessment of A:101–121 and O-B:210–228 showed them to have dissimilar solution conformation characteristics. Although O-A:101–121 failed to strongly interact with protein components of the human epithelial intestinal cell line T84, O-B:210–228 selectively associated with occludin, claudin-one and the junctional adhesion molecule (JAM)-A. Further, the presence of O-B:210–228, but not O-A:101–121, impeded the recovery of functional TJ structures. A scrambled peptide sequences of O-B:210–228 failed to influence TJ assembly. These studies demonstrate distinct properties for these two extracellular segments of the occludin protein and provide an improved understanding of how specific domains of occludin may interact with proteins present at TJ structures.


Life Sciences ◽  
2018 ◽  
Vol 192 ◽  
pp. 91-98 ◽  
Author(s):  
Guoxing Liu ◽  
Chengzhi Xie ◽  
Yu Fang ◽  
Ke Qian ◽  
Qiang Liu ◽  
...  

1998 ◽  
Vol 274 (1) ◽  
pp. F1-F9 ◽  
Author(s):  
Bradley M. Denker ◽  
Sanjay K. Nigam

Polarized epithelial cells separate two extremely different cellular milieus. The tight junction (TJ) is the most apical component of the junctional complex and serves as the permeability barrier between these environments. The tight junctional complex appears to be a dynamic and regulated structure. Some of its protein components have been identified and include the transmembrane protein occludin. Nontransmembrane proteins on the cytosolic leaflet including ZO-1, ZO-2, cingulin, 7H6, and several unidentified phosphoproteins are also believed to be part of the TJ. Interactions of some of these proteins with the actin cytoskeleton are a major determinant of TJ structure and may also play a role in the regulation of TJ assembly. Recent progress using the “calcium switch” and the “ATP depletion-repletion” model of TJ formation offers new insight regarding how these structures form. TJ biogenesis appears to be regulated, in part, by classic signal transduction pathways involving heterotrimeric G proteins, release of intracellular Ca2+, and activation of protein kinase C. Although many of the details of the signaling pathways have yet to be defined, these observations may provide insight into how TJs form during tubular development. Furthermore, it may be possible to suggest potential therapeutic targets for intervention in a variety of diseases (e.g., ischemia, toxic injury to the kidney and other epithelial tissue) where TJ integrity has been compromised and reassembly is required.


Author(s):  
T. M. Murad ◽  
Karen Israel ◽  
Jack C. Geer

Adrenal steroids are normally synthesized from acetyl coenzyme A via cholesterol. Cholesterol is also shown to enter the adrenal gland and to be localized in the lipid droplets of the adrenal cortical cells. Both pregnenolone and progesterone act as intermediates in the conversion of cholesterol into steroid hormones. During pregnancy an increased level of plasma cholesterol is known to be associated with an increase of the adrenal corticoid and progesterone. The present study is designed to demonstrate whether the adrenal cortical cells show any dynamic changes during pregnancy.


Author(s):  
Wah Chiu ◽  
David Grano

The periodic structure external to the outer membrane of Spirillum serpens VHA has been isolated by similar procedures to those used by Buckmire and Murray (1). From SDS gel electrophoresis, we have found that the isolated fragments contain several protein components, and that the crystalline structure is composed of a glycoprotein component with a molecular weight of ∽ 140,000 daltons (2). Under an electron microscopic examination, we have visualized the hexagonally-packed glycoprotein subunits, as well as the bilayer profile of the outer membrane. In this paper, we will discuss some structural aspects of the crystalline glycoproteins, based on computer-reconstructed images of the external cell wall fragments.The specimens were prepared for electron microscopy in two ways: negatively stained with 1% PTA, and maintained in a frozen-hydrated state (3). The micrographs were taken with a JEM-100B electron microscope with a field emission gun. The minimum exposure technique was essential for imaging the frozen- hydrated specimens.


Author(s):  
Daniel Beniac ◽  
George Harauz

The structures of E. coli ribosomes have been extensively probed by electron microscopy of negatively stained and frozen hydrated preparations. Coupled with quantitative image analysis and three dimensional reconstruction, such approaches are worthwhile in defining size, shape, and quaternary organisation. The important question of how the nucleic acid and protein components are arranged with respect to each other remains difficult to answer, however. A microscopical technique that has been proposed to answer this query is electron spectroscopic imaging (ESI), in which scattered electrons with energy losses characteristic of inner shell ionisations are used to form specific elemental maps. Here, we report the use of image sorting and averaging techniques to determine the extent to which a phosphorus map of isolated ribosomal subunits can define the ribosomal RNA (rRNA) distribution within them.


Author(s):  
A.J. Verkleij

Freeze-fracturing splits membranes into two helves, thus allowing an examination of the membrane interior. The 5-10 rm particles visible on both monolayers are widely assumed to be proteinaceous in nature. Most membranes do not reveal impressions complementary to particles on the opposite fracture face, if the membranes are fractured under conditions without etching. Even if it is considered that shadowing, contamination or fracturing itself might obscure complementary pits', there is no satisfactory explanation why under similar physical circimstances matching halves of other membranes can be visualized. A prominent example of uncomplementarity is found in the erythrocyte manbrane. It is wall established that band 3 protein and possibly glycophorin represents these nonccmplanentary particles. On the other hand a number of membrane types show pits opposite the particles. Scme well known examples are the ";gap junction',"; tight junction, the luminal membrane of the bladder epithelial cells and the outer membrane of Escherichia coli.


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