Apical plasma membrane-bound enzymes of rabbit uterine epithelium

1987 ◽  
Vol 87 (6) ◽  
pp. 517-529 ◽  
Author(s):  
I. Classen-Linke ◽  
H. -W. Denker ◽  
E. Winterhager
Keyword(s):  
Plasma Membrane ◽  
Uterine Epithelium ◽  
Apical Plasma Membrane ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

scholarly journals Specific Heterodimer Formation Is a Prerequisite for Uroplakins to Exit from the Endoplasmic Reticulum

2002 ◽  
Vol 13 (12) ◽  
pp. 4221-4230 ◽  
Author(s):  
Liyu Tu ◽  
Tung-Tien Sun ◽  
Gert Kreibich
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Posttranslational Modifications ◽  
Cell Layer ◽  
Building Blocks ◽  
Apical Plasma Membrane ◽  
Membrane Bound ◽  
Umbrella Cells ◽  
Vesicular Compartment ◽  
Lower Urinary

Much of the lower urinary tract, including the bladder, is lined by a stratified urothelium forming a highly differentiated, superficial umbrella cell layer. The apical plasma membrane as well as abundant cytoplasmic fusiform vesicles of the umbrella cells is covered by two-dimensional crystals that are formed by four membrane proteins named uroplakins (UPs) Ia, Ib, II, and III. UPs are synthesized on membrane-bound polysomes, and after several co- and posttranslational modifications they assemble into planar crystals in a post-Golgi vesicular compartment. Distension of the bladder may cause fusiform vesicles to fuse with the apical plasma membrane. We have investigated the early stages of uroplakin assembly by expressing the four uroplakins in 293T cells. Transfection experiments showed that, when expressed individually, only UPIb can exit from the endoplasmic reticulum (ER) and move to the plasma membrane, whereas UPII and UPIII reach the plasma membrane only when they form heterodimeric complexes with UPIa and UPIb, respectively. Heterodimer formation in the ER was confirmed by pulse-chase experiment followed by coimmunoprecipitation. Our results indicate that the initial building blocks for the assembly of crystalline uroplakin plaques are heterodimeric uroplakin complexes that form in the ER.

scholarly journals ULTRASTRUCTURAL STUDY OF MEMBRANE-BOUND ENZYMES IN THYMOCYTES

1974 ◽  
Vol 22 (12) ◽  
pp. 1128-1134 ◽  
Author(s):  
ARIANE MONNERON ◽  
JEAN-CLAUDE BENICHOU ◽  
INSTITUT PASTEUR ◽  
YVETTE FLORENTIN ◽  
ELIANE GUERRY
Keyword(s):  
Plasma Membrane ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Uridine Diphosphate ◽  
Lead Phosphate ◽  
Isolated Nuclei ◽  
Whole Cells ◽  
Diphosphate Glucose ◽  
Membrane Bound ◽  
Membrane Bound Enzymes ◽  
Phosphate Deposits

Calf thymocytes in suspension, as well as isolated calf thymocyte nuclei, were incubated in the presence of several phosphorylated substrates. 5'-Nucleotidase was easily detected on the plasma membrane of thymocytes (external side), but could be demonstrated on isolated nuclei only to a small extent. No other substrates were detectably hydrolyzed by isolated nuclei except adenosine triphosphate and 3'-thymidine monophosphate. The surface of whole cells was found to be much more reactive. A 3'-nucleotidase activity was shown to occur on the plasma membrane of a number of thymocytes and produced large lead phosphate deposits, some of them protruding into the cytoplasm. Enzymic activities splitting β-nicotinamide adenine dinucleotide phosphate and uridine diphosphate glucose were also readily detectable on the surface of cells. Since the pattern of the lead phosphate deposits and the number of reactive cells varied with the added substrate, and since cells were compared with their isolated nuclei, the positive reactions were considered to indicate the presence (on the exposed membranes) of the corresponding enzymes on the exposed membranes.

Effects of ethanol administration on rat liver plasma membrane-bound enzymes

1985 ◽  
Vol 34 (15) ◽  
pp. 2685-2689 ◽  
Author(s):  
Jorge L. Gonzalez-Calvin ◽  
John B. Saunders ◽  
Ian R. Crossley ◽  
Christopher J. Dickenson ◽  
Heather M. Smith ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Ethanol Administration ◽  
Liver Plasma Membrane ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

scholarly journals Biosynthesis and vectorial transport of opsin on vesicles in retinal rod photoreceptors.

1986 ◽  
Vol 34 (1) ◽  
pp. 5-16 ◽  
Author(s):  
D S Papermaster ◽  
B G Schneider ◽  
D DeFoe ◽  
J C Besharse
Keyword(s):  
Plasma Membrane ◽  
Outer Segment ◽  
Photoreceptor Cells ◽  
Disk Surface ◽  
Light Sensitivity ◽  
Apical Plasma Membrane ◽  
Rod Photoreceptor ◽  
Electron Microscopic ◽  
Retinal Rod ◽  
Membrane Bound

Retinal rod photoreceptor cells absorb light at one end and establish synaptic contacts on the other. Light sensitivity is conferred by a set of membrane and cytosol proteins that are gathered at one end of the cell to form a specialized organelle, the rod outer segment (ROS). The ROS is composed of rhodopsin-laden, flattened disk-shaped membranes enveloped by the cell's plasma membrane. Rhodopsin is synthesized on elements of the rough endoplasmic reticulum and Golgi apparatus near the nucleus in the inner segment. From this synthetic site, the membrane-bound apoprotein, opsin, is released from the Golgi in the membranes of small vesicles. These vesicles are transported through the cytoplasm of the inner segment until they reach its apical plasma membrane. At that site, opsin-laden vesicles appear to fuse near the base of the connecting cilium that joins the inner and outer segments. This fusion inserts opsin into the plasma membrane of the photoreceptor. Opsin becomes incorporated into the disk membrane by a process of membrane expansion and fusion to form the flattened disks of the outer segment. Within the disks, opsin is highly mobile, and rapidly rotates and traverses the disk surface. Despite its mobility in the outer segment, quantitative electron microscopic, immunocytochemical, and autoradiographic studies of opsin distribution demonstrate that little opsin is detectable in the inner segment plasma membrane, although its bilayer is in continuity with the plasma membrane of the outer segment. The photoreceptor successfully establishes the polarized distribution of its membrane proteins by restricting the redistribution of opsin after vectorially transporting it to one end of the cell on post-Golgi vesicles.

Leukotriene D4 and E4 formation by plasma membrane bound enzymes

1984 ◽  
Vol 28 (6) ◽  
pp. 929-938 ◽  
Author(s):  
Christine G. Kuo ◽  
Matthew T. Lewis ◽  
Barbara A. Jakschik
Keyword(s):  
Plasma Membrane ◽  
Leukotriene D4 ◽  
Membrane Bound ◽  
Membrane Bound Enzymes
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