Question

The enzyme that generates diacylglycerol (DAG) and inositol trisphosphate (IP3) from phosphatidylinositol bisphosphate (PIP2) is _____?

1) protein kinase C-theta (PKC-theta)
2) calcineurin
3) phospholipase C-gamma (PLC-gamma)
4) protein tyrosine kinase ZAP-70
5) protein tyrosine kinase Lck

Answer 1

The enzyme responsible for the generation of DAG and IP3 from PIP2 is phospholipase C-gamma (PLC-gamma), which plays a pivotal role in signal transduction pathways.

Step-by-step explanation:

The enzyme that generates diacylglycerol (DAG) and inositol trisphosphate (IP3) from phosphatidylinositol bisphosphate (PIP2) is phospholipase C-gamma (PLC-gamma).

Phospholipase C specifically cleaves PIP2 to form DAG and IP3, both of which serve as second messengers in signal transduction pathways. DAG remains in the plasma membrane and activates protein kinase C (PKC), while IP3 diffuses into the cytoplasm, binds to ligand-gated calcium channels in the endoplasmic reticulum, and releases Ca2+, perpetuating the signal cascade.

The function of PKC in signal transduction pathways is to initiate a phosphorylation amplification cascade through the phosphorylation of serine and threonine residues of its target proteins. PLC-gamma is particularly activated by a stimulatory G-protein after hormone binding, leading to the production of the second messengers DAG and IP3.