The binding of G-protein to rod outer segment phospholipids at the nitrogen–water interface

1989 ◽  
Vol 67 (8) ◽  
pp. 422-427 ◽  
Author(s):  
C. Salesse ◽  
F. Lamarche ◽  
R. M. Leblanc
Keyword(s):  
G Protein ◽  
Aqueous Phase ◽  
Surface Pressure ◽  
Outer Segment ◽  
Membrane Surface ◽  
Water Interface ◽  
Rod Outer Segment ◽  
Visual Process ◽  
Adsorption Desorption ◽  
Hopping Model

In the visual process, one photoexcited rhodopsin (R*) catalyzes the activation of hundreds of G-proteins. It remains to be determined whether G-protein and R* find one another by membrane surface diffusion of these components (diffusion model) or by diffusion of G-protein through the aqueous phase (hopping model). A monolayer of each main rod outer segment (ROS) phospholipid interacting with a subphase containing G-protein, has been used to simulate the interaction of G-protein with the cytoplasmic surface of discal membranes. The possible diffusion of G-protein through the aqueous phase was then measured by observing its adsorption–desorption in the monolayer of each main ROS phospholipid. From examination of surface pressure and ellipsometric isotherms at the nitrogen–water interface, we have determined that once incorporated into the monolayer, the G-protein remains associated, independent of surface pressure, thus providing evidence against the hopping model.Key words: rod outer segment, visual process, hopping model, G-protein, phospholipid monolayer, ellipsometry.

scholarly journals Characterization of bovine rod outer segment G-protein.

1982 ◽  
Vol 257 (11) ◽  
pp. 6452-6460
Author(s):  
W Baehr ◽  
E A Morita ◽  
R J Swanson ◽  
M L Applebury
Keyword(s):  
G Protein ◽  
Outer Segment ◽  
Rod Outer Segment

scholarly journals Correlation of surface pressure and hue of planarizable push–pull chromophores at the air/water interface

2017 ◽  
Vol 13 ◽  
pp. 1099-1105 ◽  
Author(s):  
Frederik Neuhaus ◽  
Fabio Zobi ◽  
Gerald Brezesinski ◽  
Marta Dal Molin ◽  
Stefan Matile ◽  
...  
Keyword(s):  
Surface Pressure ◽  
Fluorescent Probes ◽  
Color Change ◽  
Incidence Angle ◽  
Membrane Surface ◽  
Grazing Incidence ◽  
Water Interface ◽  
Lateral Membrane ◽  
Membrane Probe ◽  
Air Water Interface

It is currently not possible to directly measure the lateral pressure of a biomembrane. Mechanoresponsive fluorescent probes are an elegant solution to this problem but it requires first the establishment of a direct correlation between the membrane surface pressure and the induced color change of the probe. Here, we analyze planarizable dithienothiophene push–pull probes in a monolayer at the air/water interface using fluorescence microscopy, grazing-incidence angle X-ray diffraction, and infrared reflection–absorption spectroscopy. An increase of the lateral membrane pressure leads to a well-packed layer of the ‘flipper’ mechanophores and a clear change in hue above 18 mN/m. The fluorescent probes had no influence on the measured isotherm of the natural phospholipid DPPC suggesting that the flippers probe the lateral membrane pressure without physically changing it. This makes the flipper probes a truly useful addition to the membrane probe toolbox.

Proton Uptake by Light Induced Interaction between Rhodopsin and G-Protein

1985 ◽  
Vol 40 (5-6) ◽  
pp. 400-405 ◽  
Author(s):  
Andreas Schleicher ◽  
Klaus Peter Hofmann
Keyword(s):  
G Protein ◽  
Outer Segment ◽  
Bromocresol Purple ◽  
Rod Outer Segments ◽  
Rod Outer Segment ◽  
Outer Segments ◽  
Proton Uptake ◽  
Indicator Dye ◽  
Ph Electrode

Abstract The light-induced proton uptake of rod outer segment disc membranes has been investigated in the absence and presence of G-protein. Proton uptake was measured as the alkalisation of the suspending medium using a pH electrode and/or the indicator dye bromocresol purple. It was found that besides the known proton uptake of photolysed rhodopsin additional uptake of one proton accompanies formation of the complex between rhodopsin and G-protein. No measurable proton uptake was found under conditions of rapid redissociation of the complex indicating an only transient protonation during its lifetime. Proton uptake was the same in washed membra­nes recombined with G-protein and in ordinarily stacked rod outer segments. The additional proton uptake reported here is not due to enhanced metarhodopsin II.

scholarly journals Preparation and characterization of monoclonal antibodies to several frog rod outer segment proteins.

1984 ◽  
Vol 84 (2) ◽  
pp. 251-263 ◽  
Author(s):  
P L Witt ◽  
H E Hamm ◽  
M D Bownds
Keyword(s):  
Monoclonal Antibodies ◽  
G Protein ◽  
Protein Fraction ◽  
Outer Segment ◽  
Solid Phase ◽  
Detection System ◽  
Rod Outer Segments ◽  
Western Blots ◽  
Rod Outer Segment ◽  
Outer Segments

Monoclonal antibodies to proteins important in phototransduction in the frog rod outer segment have been obtained. These include 6 different antibodies to rhodopsin, 50 to a guanine nucleotide binding protein (G-protein; 40,000 daltons), and 2 to cytoplasmic proteins. The antigens used were Percoll-purified rod outer segments, a rod outer segment soluble protein fraction, or a soluble plus peripheral membrane protein fraction. Antibodies were assayed by solid phase assay using a fluorogenic detection system. Proteins to which antibodies bound were assayed on Western blots, and the sensitivities of three different detection systems were compared. Most antibodies bound to only one rod outer segment protein band on Western blots. Immunofluorescence microscopy demonstrated binding of both anti-rhodopsin and anti-G-protein to isolated frog rod outer segments. Antibodies were purified from either culture supernatants or ascites fluid on protein A affinity columns. Two purified anti-G-protein antibodies have binding affinities to 125I-labeled G-protein of less than 10(-6) M-1. Of 11 antibodies to frog or bovine G-protein tested in solid phase and Western blot assays, all bind to the alpha rather than the beta or gamma subunits. Procedures developed here are being used in preparing other antibodies that affect reactions in the phototransduction pathway.

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