The plasma membrane of the Funaria caulonema tip cell: morphology and distribution of particle rosettes, and the kinetics of cellulose synthesis

Planta ◽  
1984 ◽  
Vol 160 (5) ◽  
pp. 428-435 ◽  
Author(s):  
Hans-Dieter Reiss ◽  
Eberhard Schnepf ◽  
Werner Herth
Keyword(s):  
Plasma Membrane ◽  
Cell Morphology ◽  
Cellulose Synthesis ◽  
Tip Cell ◽  
Funaria Caulonema ◽  
Particle Rosettes ◽  
Kinetics Of

scholarly journals Insulin Stimulates Membrane Fusion and GLUT4 Accumulation in Clathrin Coats on Adipocyte Plasma Membranes

2007 ◽  
Vol 27 (9) ◽  
pp. 3456-3469 ◽  
Author(s):  
Shaohui Huang ◽  
Larry M. Lifshitz ◽  
Christine Jones ◽  
Karl D. Bellve ◽  
Clive Standley ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Fusion ◽  
Insulin Signaling ◽  
Plasma Membranes ◽  
Glucose Transporter ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Tirf Microscopy ◽  
Adipocyte Plasma Membranes ◽  
Kinetics Of

ABSTRACT Total internal reflection fluorescence (TIRF) microscopy reveals highly mobile structures containing enhanced green fluorescent protein-tagged glucose transporter 4 (GLUT4) within a zone about 100 nm beneath the plasma membrane of 3T3-L1 adipocytes. We developed a computer program (Fusion Assistant) that enables direct analysis of the docking/fusion kinetics of hundreds of exocytic fusion events. Insulin stimulation increases the fusion frequency of exocytic GLUT4 vesicles by ∼4-fold, increasing GLUT4 content in the plasma membrane. Remarkably, insulin signaling modulates the kinetics of the fusion process, decreasing the vesicle tethering/docking duration prior to membrane fusion. In contrast, the kinetics of GLUT4 molecules spreading out in the plasma membrane from exocytic fusion sites is unchanged by insulin. As GLUT4 accumulates in the plasma membrane, it is also immobilized in punctate structures on the cell surface. A previous report suggested these structures are exocytic fusion sites (Lizunov et al., J. Cell Biol. 169:481-489, 2005). However, two-color TIRF microscopy using fluorescent proteins fused to clathrin light chain or GLUT4 reveals these structures are clathrin-coated patches. Taken together, these data show that insulin signaling accelerates the transition from docking of GLUT4-containing vesicles to their fusion with the plasma membrane and promotes GLUT4 accumulation in clathrin-based endocytic structures on the plasma membrane.

The effects of acetylcholine and atropine on the 22Na+ permeability of intestinal smooth muscle vesicles

1978 ◽  
Vol 56 (6) ◽  
pp. 921-925
Author(s):  
L. Spero
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Membrane Vesicles ◽  
Intestinal Smooth Muscle ◽  
Erythrocyte Ghosts ◽  
Muscarinic Agonists ◽  
Plasma Membrane Vesicles ◽  
Muscle Plasma Membrane ◽  
Whole Muscle ◽  
Kinetics Of

A technique is described which has enabled us to measure changes in 22Na+ efflux from smooth muscle plasma membrane vesicles. The resting 22Na+ efflux from these sealed vesicles showed a concentration-dependent increase in response to acetylcholine and other muscarinic agonists, in similar concentrations to those which increased 42K+ efflux in whole muscle. The kinetics of this efflux were complex and could not be described by less than three exponential processes. The response to agonists has, therefore, been characterized by measurement of the half-life of 22Na+ efflux (t1/2). The acetylcholine effect was inhibited by atropine, but unlike the situation in the whole muscle, this inhibition was noncompetitive. Tubocuraine (a nicotinic antagonist) had no effect on this acetylcholine response. Atropine has no effect by itself on the resting 22Na+ efflux, neither did tetrodotoxin or ouabain. 22Na+ efflux from erythrocyte ghosts and liposomes, prepared from lipid extracts of the smooth muscle plasma membrane, was not modified by acetylcholine or atropine.

scholarly journals Activation Kinetics of RAF Protein in the Ternary Complex of RAF, RAS-GTP, and Kinase on the Plasma Membrane of Living Cells

2011 ◽  
Vol 286 (42) ◽  
pp. 36460-36468 ◽  
Author(s):  
Kayo Hibino ◽  
Tatsuo Shibata ◽  
Toshio Yanagida ◽  
Yasushi Sako
Keyword(s):  
Plasma Membrane ◽  
Ternary Complex ◽  
Living Cells ◽  
Activation Kinetics ◽  
Kinetics Of

Mechanisms of micronutrient uptake in plants

2001 ◽  
Vol 28 (7) ◽  
pp. 661 ◽  
Author(s):  
Robert J. Reid
Keyword(s):  
Plasma Membrane ◽  
Trace Metals ◽  
Plant Growth ◽  
Expression Systems ◽  
Cation Uptake ◽  
Micronutrient Uptake ◽  
Heterologous Expression Systems ◽  
Metal Micronutrients ◽  
Uptake Studies ◽  
Kinetics Of

In plants, the elements Fe, Zn, Mn, Cu, Ni, B, Mo and Cl are considered to be micronutrients essential for plant growth. Micronutrient uptake systems are intrinsically more difficult to investigate than their macronutrient counterparts because of the low fluxes involved. Currently, the mechanism of transport for these micronutrients has not been clearly identified, except for Cl. In the case of the trace metal micronutrients, uptake studies point to the presence of high and low affinity transporters with broad substrate specificity. The kinetics of these transporters is clouded by the failure of many investigators to consider the effects of the electrostatic nature of the plasma membrane on cation uptake. Recent work has helped to clarify the nature of B movement across membranes and there is now evidence of a facilitated transport system for B, in addition to its passive permeation directly through the membrane. The uptake of Mo is known to be induced by NO3 and inhibited by W, but little further information is available on how Mo enters cells. In recent years, the emphasis has shifted from physiological studies of micronutrient uptake to molecular investigations of transporters cloned in plants and characterized in heterologous expression systems. There is now a substantial catalogue of transporter genes, mostly for trace metals, whose functions in plants have yet to be clearly defined.

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