| Autor: |
Biernbaum MS; Laboratory of Molecular Biology, University of Wisconsin, Madison 53706., Binder BM, Bownds MD |
| Jazyk: |
angličtina |
| Zdroj: |
Visual neuroscience [Vis Neurosci] 1991 Nov; Vol. 7 (5), pp. 499-503. |
| DOI: |
10.1017/s0952523800009780 |
| Abstrakt: |
The phosphorylation of photoexcited rhodopsin (Rho*) is thought to inactivate this receptor by inhibiting its interaction with the GTP-binding protein transducin (Gt). Here we report that the time course of phosphorylation-dephosphorylation after bright illumination of intact rod outer and inner segments (ROS-RIS) incubated in 33Pi can be altered if the ROS-RIS are first exposed to levels of dim illumination that cause light adaptation in these ROS-RIS. The dephosphorylation of greater than 10(7) phosphorylated rhodopsin molecules/ROS following a bright flash can be blocked by prior dim continuous illumination (generating 10(3) Rho*/ROS/s) that cumulatively bleaches approximately 10(5) rhodopsin molecules/ROS. The phenomenon has not been previously noted because these low levels of light are emitted as a result of Cerenkov radiation from the 32P isotope that is usually employed to monitor rhodopsin phosphorylation. The inhibition of rhodopsin dephosphorylation by dim conditioning illumination is observed in intact ROS-RIS but is lost when ROS-RIS are electropermeabilized or fragmented. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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