Question

The figure depicts the calcium and IP₃ signaling pathway:


© 2012 FLVS

A scientist compares two cells, Cell A and Cell B, and notes that Cell B has a higher phospholipase C content than Cell A. Assuming no other factors are affecting this pathway, what can be said about the likely concentration of PIP₂ in Cell B compared to Cell A?

Phospholipase C will have no effect on the PIP₂ concentration.

PIP₂ will be in a higher concentration in Cell B.

PIP₂ will be in a lower concentration in Cell B.

PIP₂ will be in the same concentration in both cells

Answer 1

The correct answer is-

c- PIP2 will be in a lower concentration in Cell B.

The G-protein-coupled receptor stimulates an enzyme known as phospholipase C upon binding of the ligand on the receptor. Phosphalipase C plays an important role in hydrolysis of PIP2 and this hydrolysis reeaction produces intracellular mediators such as IP3 (inositol triphosphate) and DAG (diacylglycerol).

Since cell B has higher phospholipase C content than Cell A, more PIP2 will be hydrolysed in cell B. Thus the concentration of PIP2 will be lower in cell B.