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Calcium pump in the disk membranes isolated from bovine retinal rod outer segments
I Panfoli1, A Morelli, I M Pepe
1Istituto Policattedra di Chimica Biologica, Università, Genoa, Italy.
Journal of Photochemistry and Photobiology. B, Biology
|August 1, 1994
Summary
Researchers found evidence of a calcium pump in bovine retinal rod outer segments. This pump is crucial for regulating calcium levels during photoreceptor cell function.
Area of Science:
- Biochemistry
- Cell Biology
- Neuroscience
Background:
- Rod outer segments are key to vision.
- Calcium ion (Ca2+) regulation is vital for photoreceptor function.
Purpose of the Study:
- To investigate the presence and function of a Ca2+ pump in bovine retinal rod outer segment disks.
Main Methods:
- Isolation of a phosphorylated intermediate using sodium dodecyl sulfate polyacrylamide gel electrophoresis.
- Measurement of active calcium transport and adenosine 5'-triphosphate (ATP) hydrolysis.
- Analysis of Ca2+ uptake and ATP hydrolysis under various conditions (e.g., Mg2+-ATP, vanadate, lanthanum, calmodulin).
Main Results:
- A hydroxylamine-sensitive phosphorylated intermediate (E-P) of ~100 kDa was identified.
- Active Ca2+ uptake required Mg2+-ATP and was inhibited by vanadate and lanthanum.
- ATP hydrolysis was dependent on free Ca2+ concentration.
Conclusions:
- Evidence strongly suggests the presence of a Ca2+ pump in rod outer segment disks.
- This Ca2+ pump likely plays a role in buffering Ca2+ ions during photoreceptor cell activity.