The normal signal response initiated by certain growth factor-receptor interactions is an increase in the activity of protein kinase C (PKC). The activity of PKC is controlled by both calcium ion and lipid, particularly diacylglycerols. Abnormal cells hat do not exhibit normal activation of PKC in response to addition of growth factor would most likely be lacking in the ability to synthesize which of the following class of phospholipid?
A) cardiolipin
B) phosphatidylcholine
C) phosphatidylethanolamine
D) phosphatidylinositol
E) phosphatidylserine

Question

Quizplus · Accepted Answer

Phosphatidylinositol is a precursor for diacylglycerol, which is necessary for PKC activation. Phosphatidylinositols with phosphorylated inositol are termed polyphosphoinositides. The polyphosphoinositides are important intracellular transducers of signals emanating from the plasma membrane. One polyphosphoinositide (phosphatidylinositol 4,5-bisphosphate, PIP₂) is a critically important membrane phospholipid involved in the transmission of signals for cell growth and differentiation from outside the cell to inside. Numerous G-protein- coupled receptors activate phospholipase A2, which releases diacylglycerol (DAG) and inositol trisphosphate (IP₂) from PIP₂. The IP₂ binds to receptors on ER membranes resulting in the release of stored calcium into the cytosol.

The Normal Signal Response Initiated by Certain Growth Factor-Receptor Interactions