In the phospholipase C mechanism,most of the increased intracellular calcium comes from
A)outside the cell.
B)within the plasma membrane.
C)the endoplasmic reticulum.
D)extracellular fluiD.

Question

Quizplus · Accepted Answer

The majority of the increased intracellular calcium in the phospholipase C mechanism comes from the endoplasmic reticulum, specifically the sarcoplasmic reticulum in muscle cells. This is because the enzyme phospholipase C cleaves a particular phospholipid in the plasma membrane, generating inositol triphosphate (IP3) which can then bind to IP3 receptors on the endoplasmic reticulum, causing release of stored calcium into the cytoplasm. While some calcium may also enter the cell from the extracellular fluid or be present within the plasma membrane, these sources generally contribute less to the overall increase in intracellular calcium seen in response to phospholipase C activation.

In the Phospholipase C Mechanism,most of the Increased Intracellular Calcium