title: Light- and nucleotide-dependent increase in apparent viscosity in a suspension of retinal disks.
abstract: Light triggers the cyclic nucleotide cascade in photoreceptor disk membranes. We report here that light-induced changes in the apparent viscosity of disk membrane suspensions can also be observed using either native disk membranes or washed membranes reconstituted with G protein and PDE. The viscosity changes are light- and GTP-dependent and require the presence of G protein and PDE. The magnitude of the viscosity change increases with increasing membrane concentration. Under the same conditions in which light elicits a change in viscosity, we observe a large increase in light scattering by the disk membrane suspension.
mesh_terms: D000818:Animals; D002024:Bufo marinus; D002417:Cattle; D003623:Dark Adaptation; D005136:Eye Proteins / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D020962:Heterotrimeric GTP-Binding Proteins; D008027:Light; D009711:Nucleotides / Q000502:physiology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D010786:Photoreceptor Cells / Q000378:metabolism* / Q000528:radiation effects; D012243:Rhodopsin / Q000378:metabolism; D012542:Scattering, Radiation; D013873:Thionucleotides / Q000494:pharmacology; D015293:Transducin; D014783:Viscosity
chemical_list: D005136:Eye Proteins; C034809:GNAT1 protein, human; D009711:Nucleotides; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D012243:Rhodopsin; D010727:Phosphoric Diester Hydrolases; D020962:Heterotrimeric GTP-Binding Proteins; D015293:Transducin