54 out of 95
Which of the following substance increase the release of Ca++ from endoplasmic reticulum?
|C||1, 25-dihydroxy cholecalciferol|
Ans. A Inositol triphosphate
- Inositol, 4, 5-triphosphate (a inositol derivative) bind to receptors on the endoplasmic reticulum, causing a rapid release of Ca++ from intracellular stores.
- The resulting increase in intracellular Ca++ permits the formation of a calcium calmodulin complex that mediates a wide range of effects of ~e intracellular Ca ++
- Calmodulin is the most widely distributed small calcium-binding proteins.
- The binding of 4 molecules of Ca++ to calmodulin triggers a conformational change such that the activated Ca ++ calmodulin complex bind to the and activates protein molecules, often enzymes.