scholarly journals Caveolins, a Family of Scaffolding Proteins for Organizing “Preassembled Signaling Complexes” at the Plasma Membrane

1998 ◽  
Vol 273 (10) ◽  
pp. 5419-5422 ◽  
Author(s):  
Takashi Okamoto ◽  
Amnon Schlegel ◽  
Philipp E. Scherer ◽  
Michael P. Lisanti
Keyword(s):  
Plasma Membrane ◽  
Scaffolding Proteins

scholarly journals Characterization of TSET, an ancient and widespread membrane trafficking complex

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Jennifer Hirst ◽  
Alexander Schlacht ◽  
John P Norcott ◽  
David Traynor ◽  
Gareth Bloomfield ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Scaffolding Proteins ◽  
Eukaryotic Evolution ◽  
Bioinformatics Tool ◽  
Membrane Turnover ◽  
Evolutionary Path ◽  
The Core ◽  
Eukaryotic Supergroup

The heterotetrameric AP and F-COPI complexes help to define the cellular map of modern eukaryotes. To search for related machinery, we developed a structure-based bioinformatics tool, and identified the core subunits of TSET, a 'missing link' between the APs and COPI. Studies in Dictyostelium indicate that TSET is a heterohexamer, with two associated scaffolding proteins. TSET is non-essential in Dictyostelium, but may act in plasma membrane turnover, and is essentially identical to the recently described TPLATE complex, TPC. However, whereas TPC was reported to be plant-specific, we can identify a full or partial complex in every eukaryotic supergroup. An evolutionary path can be deduced from the earliest origins of the heterotetramer/scaffold coat to its multiple manifestations in modern organisms, including the mammalian muniscins, descendants of the TSET medium subunits. Thus, we have uncovered the machinery for an ancient and widespread pathway, which provides new insights into early eukaryotic evolution.

Signaling pathways are focused at specialized regions of the plasma membrane by scaffolding proteins of the MAGUK family

BioEssays ◽  
1999 ◽  
Vol 21 (11) ◽  
pp. 912-921 ◽  
Author(s):  
Spiros D. Dimitratos ◽  
Daniel F. Woods ◽  
Dean G. Stathakis ◽  
Peter J. Bryant
Keyword(s):  
Plasma Membrane ◽  
Signaling Pathways ◽  
Scaffolding Proteins

scholarly journals Apical–basal polarity in Drosophila neuroblasts is independent of vesicular trafficking

2011 ◽  
Vol 22 (22) ◽  
pp. 4373-4379 ◽  
Author(s):  
Nils Halbsgut ◽  
Karen Linnemannstöns ◽  
Laura Isabel Zimmermann ◽  
Andreas Wodarz
Keyword(s):  
Plasma Membrane ◽  
Cell Types ◽  
Vesicular Trafficking ◽  
Scaffolding Proteins ◽  
Par Proteins ◽  
Evolutionarily Conserved ◽  
A Cell ◽  
Cellular Machinery ◽  
Basolateral Plasma Membrane ◽  
Cell Type Specific

The possession of apical–basal polarity is a common feature of epithelia and neural stem cells, so-called neuroblasts (NBs). In Drosophila, an evolutionarily conserved protein complex consisting of atypical protein kinase C and the scaffolding proteins Bazooka/PAR-3 and PAR-6 controls the polarity of both cell types. The components of this complex localize to the apical junctional region of epithelial cells and form an apical crescent in NBs. In epithelia, the PAR proteins interact with the cellular machinery for polarized exocytosis and endocytosis, both of which are essential for the establishment of plasma membrane polarity. In NBs, many cortical proteins show a strongly polarized subcellular localization, but there is little evidence for the existence of distinct apical and basolateral plasma membrane domains, raising the question of whether vesicular trafficking is required for polarization of NBs. We analyzed the polarity of NBs mutant for essential regulators of the main exocytic and endocytic pathways. Surprisingly, we found that none of these mutations affected NB polarity, demonstrating that NB cortical polarity is independent of plasma membrane polarity and that the PAR proteins function in a cell type–specific manner.

scholarly journals Antagonistic Functions of Two Stardust Isoforms in Drosophila Photoreceptor Cells

2010 ◽  
Vol 21 (22) ◽  
pp. 3915-3925 ◽  
Author(s):  
Natalia A. Bulgakova ◽  
Michaela Rentsch ◽  
Elisabeth Knust
Keyword(s):  
Plasma Membrane ◽  
Retinal Degeneration ◽  
Protein Complexes ◽  
Photoreceptor Cells ◽  
Modular Organization ◽  
Apical Plasma Membrane ◽  
Scaffolding Proteins ◽  
Restricted Region ◽  
Stalk Length

Membrane-associated guanylate kinases (MAGUKs) are scaffolding proteins that organize supramolecular protein complexes, thereby partitioning the plasma membrane into spatially and functionally distinct subdomains. Their modular organization is ideally suited to organize protein complexes with cell type- or stage-specific composition, or both. Often more than one MAGUK isoform is expressed by one gene in the same cell, yet very little is known about their individual in vivo functions. Here, we show that two isoforms of Drosophila stardust, Sdt-H (formerly called Sdt-B2) and Sdt-D, which differ in their N terminus, are expressed in adult photoreceptors. Both isoforms associate with Crumbs and PATJ, constituents of the conserved Crumbs–Stardust complex. However, they form distinct complexes, localized at the stalk, a restricted region of the apical plasma membrane. Strikingly, Sdt-H and Sdt-D have antagonistic functions. While Sdt-H overexpression increases stalk membrane length and prevents light-dependent retinal degeneration, Sdt-D overexpression reduces stalk length and enhances light-dependent retinal degeneration. These results suggest that a fine-tuned balance of different Crumbs complexes regulates photoreceptor homeostasis.

scholarly journals Possible Involvement of Tight Junctions, Extracellular Matrix and Nuclear Receptors in Epithelial Differentiation

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Naoki Ichikawa-Tomikawa ◽  
Kotaro Sugimoto ◽  
Seiro Satohisa ◽  
Keisuke Nishiura ◽  
Hideki Chiba
Keyword(s):  
Extracellular Matrix ◽  
Plasma Membrane ◽  
Tight Junctions ◽  
Nuclear Receptors ◽  
Functional Significance ◽  
Transmembrane Proteins ◽  
Intercellular Junctions ◽  
Epithelial Differentiation ◽  
Scaffolding Proteins ◽  
Fence Function

Tight junctions are intercellular junctions localized at the most apical end of the lateral plasma membrane. They consist of four kinds of transmembrane proteins (occludin, claudins, junctional adhesion molecules, and tricellulin) and huge numbers of scaffolding proteins and contribute to the paracellular barrier and fence function. The mutation and deletion of these proteins impair the functions of tight junctions and cause various human diseases. In this paper, we provide an overview of recent studies on transmembrane proteins of tight junctions and highlight the functional significance of tight junctions, extracellular matrix, and nuclear receptors in epithelial differentiation.

Compartmentalization of adenylate cyclase and cAMP signalling

2005 ◽  
Vol 33 (6) ◽  
pp. 1319-1322 ◽  
Author(s):  
D.M.F. Cooper
Keyword(s):  
Plasma Membrane ◽  
Signalling Pathways ◽  
Scaffolding Proteins ◽  
Subcellular Targeting ◽  
Camp Signalling ◽  
Cellular Processes ◽  
Cyclic Nucleotide Gated Channels ◽  
Anchoring Protein ◽  
Raft Domains ◽  
Kinase A

Concepts of cAMP signalling have changed dramatically from the linear cascades of just a few years ago, with the realization that numerous cellular processes affect this motif. These influences include other signalling pathways – most significantly Ca2+, scaffolding proteins (which are themselves variously regulated) to organize the elements of the pathway, and subcellular targeting of components. An obvious implication of this organization is that global measurements of cAMP may trivialize the complexity of the cAMP signals and obscure the regulation of targets. In this presentation, current developments on the targeting and assembly of ACs (adenylate cyclases) and their delivery to selected raft or non-raft domains of the plasma membrane will be discussed, along with the susceptibility of raft-targeted ACs to very discrete modes of increases in the intracellular Ca2+ concentration. Single-cell explorations of cAMP dynamics, as measured with cyclic nucleotide-gated channels, are also described in this paper, particularly as applied to cells in which the composition of AKAP (A-kinase anchoring protein)–PKA (protein kinase A)–PDE (phosphodiesterase) assemblies is probed by RNA interference ablation of defined AKAPs.

Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

1977 ◽  
Vol 35 ◽  
pp. 596-597
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Candida Utilis ◽  
Synthetic Medium ◽  
Freeze Fracture ◽  
Translational Diffusion ◽  
Yeast Cells ◽  
Distilled Water ◽  
Intramembrane Particles ◽  
The Matrix ◽  
Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

Organization of the Pellicle and the Muciferous Glands in Euglena Gracilis

1970 ◽  
Vol 28 ◽  
pp. 104-105
Author(s):  
Hilton H. Mollenhauer ◽  
W. Evans
Keyword(s):  
Plasma Membrane ◽  
Euglena Gracilis ◽  
Complex Forms ◽  
Secondary Periodicity

The pellicular structure of Euglena gracilis consists of a series of relatively rigid strips (Fig. 1) composed of ridges and grooves which are helically oriented along the cell and which fuse together into a common junction at either end of the cell. The strips are predominantly protein and consist in part of a series of fibers about 50 Å in diameter spaced about 85 Å apart and with a secondary periodicity of about 450 Å. Microtubules are also present below each strip (Fig. 1) and are often considered as part of the pellicular complex. In addition, there may be another fibrous component near the base of the pellicle which has not yet been very well defined.The pellicular complex lies underneath the plasma membrane and entirely within the cell (Fig. 1). Each strip of the complex forms an overlapping junction with the adjacent strip along one side of each groove (Fig. 1), in such a way that a certain amount of sideways movement is possible between one strip and the next.

Localization of Sodium in Normal and Inhibited Transporting Epithelia

1971 ◽  
Vol 29 ◽  
pp. 392-393
Author(s):  
G. I. Kaye ◽  
J. D. Cole
Keyword(s):  
Plasma Membrane ◽  
Similar Pattern ◽  
Fixation Method ◽  
Colonic Epithelium ◽  
Gallbladder Epithelium ◽  
Rabbit Colon ◽  
Rabbit Gallbladder

For a number of years we have used an adaptation of Komnick's KSb(OH)6-OsO4 fixation method for the localization of sodium in tissues in order to study transporting epithelia under a number of different conditions. We have shown that in actively transporting rabbit gallbladder epithelium, large quantities of NaSb(OH)6 precipitate are found in the distended intercellular compartment, while localization of precipitate is confined to the inner side of the lateral plasma membrane in inactive gallbladder epithelium. A similar pattern of distribution of precipitate has been demonstrated in human and rabbit colon in active and inactive states and in the inactive colonic epithelium of hibernating frogs.

Electron microscopy of endocardial cell populations

1978 ◽  
Vol 36 (2) ◽  
pp. 486-487
Author(s):  
T. G. Sarphie ◽  
C. R. Comer ◽  
D. J. Allen
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Cellular Transformation ◽  
Cell Populations ◽  
Cell Surfaces ◽  
Kb Cells ◽  
Dna Viruses ◽  
Cell Cycles ◽  
Ultrastructural Studies ◽  
Endocardial Cell

Previous ultrastructural studies have characterized surface morphology during norma cell cycles in an attempt to associate specific changes with specific metabolic processes occurring within the cell. It is now known that during the synthetic ("S") stage of the cycle, when DNA and other nuclear components are synthesized, a cel undergoes a doubling in volume that is accompanied by an increase in surface area whereby its plasma membrane is elaborated into a variety of processes originally referred to as microvilli. In addition, changes in the normal distribution of glycoproteins and polysaccharides derived from cell surfaces have been reported as depreciating after cellular transformation by RNA or DNA viruses and have been associated with the state of growth, irregardless of the rate of proliferation. More specifically, examination of the surface carbohydrate content of synchronous KB cells were shown to be markedly reduced as the cell population approached division Comparison of hamster kidney fibroblasts inhibited by vinblastin sulfate while in metaphase with those not in metaphase demonstrated an appreciable decrease in surface carbohydrate in the former.

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