scholarly journals Calcium-Dependent Phosphorylation of Symbiosome Membrane Proteins from Nitrogen-Fixing Soybean Nodules

1991 ◽  
Vol 95 (1) ◽  
pp. 222-227 ◽  
Author(s):  
C. David Weaver ◽  
Burnette Crombie ◽  
Gary Stacey ◽  
Daniel M. Roberts
Keyword(s):  
Membrane Proteins ◽  
Nitrogen Fixing ◽  
Calcium Dependent ◽  
Symbiosome Membrane

scholarly journals Iron Transport across Symbiotic Membranes of Nitrogen-Fixing Legumes

2021 ◽  
Vol 22 (1) ◽  
pp. 432
Author(s):  
David A. Day ◽  
Penelope M. C. Smith
Keyword(s):  
Iron Transport ◽  
Root Nodules ◽  
Nitrogen Fixing ◽  
High Demand ◽  
Symbiosome Membrane ◽  
Essential Nutrient ◽  
Infected Cells ◽  
Very High

Iron is an essential nutrient for the legume-rhizobia symbiosis and nitrogen-fixing bacteroids within root nodules of legumes have a very high demand for the metal. Within the infected cells of nodules, the bacteroids are surrounded by a plant membrane to form an organelle-like structure called the symbiosome. In this review, we focus on how iron is transported across the symbiosome membrane and accessed by the bacteroids.

Biochemical characterization of symbiosome membrane proteins fromMedicago truncatula root nodules

2004 ◽  
Vol 25 (3) ◽  
pp. 519-531 ◽  
Author(s):  
Christina M. Catalano ◽  
William S. Lane ◽  
D. Janine Sherrier
Keyword(s):  
Membrane Proteins ◽  
Biochemical Characterization ◽  
Root Nodules ◽  
Symbiosome Membrane

scholarly journals Motion Matters: Secretory Granule Motion Adjacent to the Plasma Membrane and Exocytosis

2006 ◽  
Vol 17 (5) ◽  
pp. 2424-2438 ◽  
Author(s):  
Miriam W. Allersma ◽  
Mary A. Bittner ◽  
Daniel Axelrod ◽  
Ronald W. Holz
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Fluorescence Microscopy ◽  
Total Internal Reflection ◽  
Chromaffin Cells ◽  
Actin Dynamics ◽  
Permeabilized Cells ◽  
Calcium Dependent ◽  
Individual Granule ◽  
Granule Motion

Total internal reflection fluorescence microscopy was used to monitor changes in individual granule motions related to the secretory response in chromaffin cells. Because the motions of granules are very small (tens of nanometers), instrumental noise in the quantitation of granule motion was taken into account. ATP and Ca2+, both of which prime secretion before fusion, also affect granule motion. Removal of ATP in permeabilized cells causes average granule motion to decrease. Nicotinic stimulation causes a calcium-dependent increase in average granule motion. This effect is more pronounced for granules that undergo exocytosis than for those that do not. Fusion is not preceded by a reduction in mobility. Granules sometimes move 100 nm or more up to and within a tenth of a second before fusion. Thus, the jittering motion of granules adjacent to the plasma membrane is regulated by factors that regulate secretion and may play a role in secretion. Motion continues until shortly before fusion, suggesting that interaction of granule and plasma membrane proteins is transient. Disruption of actin dynamics did not significantly alter granule motion.

scholarly journals Similarities and differences in the structure and function of 4.1G and 4.1R135, two protein 4.1 paralogues expressed in erythroid cells

2010 ◽  
Vol 432 (2) ◽  
pp. 407-416 ◽  
Author(s):  
Wataru Nunomura ◽  
Kengo Kinoshita ◽  
Marilyn Parra ◽  
Philippe Gascard ◽  
Xiuli An ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Erythroid Differentiation ◽  
Band 3 ◽  
Erythroid Cells ◽  
Protein 4.1 ◽  
Calcium Dependent ◽  
Calmodulin Binding ◽  
And Function ◽  
Glycophorin C ◽  
In Erythroid Cells

Membrane skeletal protein 4.1R is the prototypical member of a family of four highly paralogous proteins that include 4.1G, 4.1N and 4.1B. Two isoforms of 4.1R (4.1R135 and 4.1R80), as well as 4.1G, are expressed in erythroblasts during terminal differentiation, but only 4.1R80 is present in mature erythrocytes. Although the function of 4.1R isoforms in erythroid cells has been well characterized, there is little or no information on the function of 4.1G in these cells. In the present study, we performed detailed characterization of the interaction of 4.1G with various erythroid membrane proteins and the regulation of these interactions by calcium-saturated calmodulin. Like both isoforms of 4.1R, 4.1G bound to band 3, glycophorin C, CD44, p55 and calmodulin. While both 4.1G and 4.1R135 interact with similar affinity with CD44 and p55, there are significant differences in the affinity of their interaction with band 3 and glycophorin C. This difference in affinity is related to the non-conserved N-terminal headpiece region of the two proteins that is upstream of the 30 kDa membrane-binding domain that harbours the binding sites for the various membrane proteins. The headpiece region of 4.1G also contains a high-affinity calcium-dependent calmodulin-binding site that plays a key role in modulating its interaction with various membrane proteins. We suggest that expression of the two paralogues of protein 4.1 with different affinities for band 3 and glycophorin C is likely to play a role in assembly of these two membrane proteins during terminal erythroid differentiation.

Changes Occur in Plasma Membrane Turnover when K562 Leukemia Cells are Induced to Differentiate

1982 ◽  
Vol 40 ◽  
pp. 286-287
Author(s):  
L. M. Marshall
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Intracellular Transport ◽  
Parent Cell ◽  
Membrane Turnover ◽  
Coated Pits ◽  
Surface Distribution ◽  
Specific Proteins ◽  
Erythroleukemic Cell ◽  
Specific Membrane

A human erythroleukemic cell line, metabolically blocked in a late stage of erythropoiesis, becomes capable of differentiation along the normal pathway when grown in the presence of hemin. This process is characterized by hemoglobin synthesis followed by rearrangement of the plasma membrane proteins and culminates in asymmetrical cytokinesis in the absence of nuclear division. A reticulocyte-like cell buds from the nucleus-containing parent cell after erythrocyte specific membrane proteins have been sequestered into its membrane. In this process the parent cell faces two obstacles. First, to organize its erythrocyte specific proteins at one pole of the cell for inclusion in the reticulocyte; second, to reduce or abolish membrane protein turnover since hemoglobin is virtually the only protein being synthesized at this stage. A means of achieving redistribution and cessation of turnover could involve movement of membrane proteins by a directional lipid flow. Generation of a lipid flow towards one pole and accumulation of erythrocyte-specific membrane proteins could be achieved by clathrin coated pits which are implicated in membrane endocytosis, intracellular transport and turnover. In non-differentiating cells, membrane proteins are turned over and are random in surface distribution. If, however, the erythrocyte specific proteins in differentiating cells were excluded from endocytosing coated pits, not only would their turnover cease, but they would also tend to drift towards and collect at the site of endocytosis. This hypothesis requires that different protein species are endocytosed by the coated vesicles in non-differentiating than by differentiating cells.

Image Analysis of Intramembrane Particles in Freeze-Fractured Biomembranes Using Computer Simulation Techniques

1975 ◽  
Vol 33 ◽  
pp. 214-215
Author(s):  
D.J. Benefiel ◽  
R.S. Weinstein
Keyword(s):  
Membrane Proteins ◽  
Freeze Fracture ◽  
Integral Membrane Proteins ◽  
Systematic Evaluation ◽  
Intramembrane Particles ◽  
Modeling Methods ◽  
Simulation Techniques ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron ◽  
Computer Simulation Techniques

Intramembrane particles (IMP or MAP) are components of most biomembranes. They are visualized by freeze-fracture electron microscopy, and they probably represent replicas of integral membrane proteins. The presence of MAP in biomembranes has been extensively investigated but their detailed ultrastructure has been largely ignored. In this study, we have attempted to lay groundwork for a systematic evaluation of MAP ultrastructure. Using mathematical modeling methods, we have simulated the electron optical appearances of idealized globular proteins as they might be expected to appear in replicas under defined conditions. By comparing these images with the apearances of MAPs in replicas, we have attempted to evaluate dimensional and shape distortions that may be introduced by the freeze-fracture technique and further to deduce the actual shapes of integral membrane proteins from their freezefracture images.

A Novel Reconstitution Method for Inducing the Formation of Regular 2-Dimensional Arrays of Membrane Proteins and Lipids

1988 ◽  
Vol 46 ◽  
pp. 152-153 ◽  
Author(s):  
A. Engel ◽  
A. Holzenburg ◽  
K. Stauffer ◽  
J. Rosenbusch ◽  
U. Aebi
Keyword(s):  
Membrane Proteins ◽  
Flow Rate ◽  
Lipid Membranes ◽  
Functional Characterization ◽  
Dimensional Structure ◽  
Electron Crystallography ◽  
Peltier Element ◽  
Protein Ratio ◽  
Precise Control ◽  
3 Dimensional

Reconstitution of solubilized and purified membrane proteins in the presence of phospholipids into vesicles allows their functions to be studied by simple bulk measurements (e.g. diffusion of differently sized solutes) or by conductance measurements after transformation into planar membranes. On the other hand, reconstitution into regular protein-lipid arrays, usually forming at a specific lipid-to-protein ratio, provides the basis for determining the 3-dimensional structure of membrane proteins employing the tools of electron crystallography.To refine reconstitution conditions for reproducibly inducing formation of large and highly ordered protein-lipid membranes that are suitable for both electron crystallography and patch clamping experiments aimed at their functional characterization, we built a flow-dialysis device that allows precise control of temperature and flow-rate (Fig. 1). The flow rate is generated by a peristaltic pump and can be adjusted from 1 to 500 ml/h. The dialysis buffer is brought to a preselected temperature during its travel through a meandering path before it enters the dialysis reservoir. A Z-80 based computer controls a Peltier element allowing the temperature profile to be programmed as function of time.

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