Interaction of bovine rhodopsin with calcium ions. II: calcium release in bovine rod outer segments upon bleaching.
The calcium content of bovine rod outer segment (ROS) suspensions was determined by flame spectrophotometry to be about 0.2 Ca2+ per molecule rhodopsin. After bleaching of rhodopsin, a release of 0.01--0.1 Ca2+ per molecule rhodopsin from ROS into the solution was observed. These figures agree with some data in the literature (Appendix). A measured absorption increase of the Ca2+-indicator phthalein purple (10 degrees C, 562 nm, pH 9.3) occurs apparently simultaneously with the formation of metarhodopsin ii in ROS. This indicates that a light induced Ca2+-release of 12 calcium ions per photoactivated rhodopsin is coupled in time with the formation of metarhodopsin II.
D000042:Absorption; D000818:Animals; D002118:Calcium / Q000032:analysis / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D002417:Cattle; D004396:Coloring Agents; D007202:Indicators and Reagents; D008027:Light; D010786:Photoreceptor Cells / Q000032:analysis / Q000378:metabolism* / Q000528:radiation effects; D012168:Retinal Pigments / Q000502:physiology*; D012243:Rhodopsin / Q000502:physiology*; D013053:Spectrophotometry
D004396:Coloring Agents; D007202:Indicators and Reagents; D012168:Retinal Pigments; D012243:Rhodopsin; D002118:Calcium