The binding of G-protein to rod outer segment phospholipids at the nitrogen-water interface.
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.
Salesse
C
C
Institut für Organische Chemie, Mainz Universität, Federal Republic of Germany.
Lamarche
F
F
Leblanc
R M
RM
D000818:Animals; D002417:Cattle; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000378:metabolism*
D008565:Membrane Proteins; D010743:Phospholipids; D019204:GTP-Binding Proteins