Question

How does IP3 function in the inositol phospholipid pathway?Choose one:

A. It produces diacylglycerol.
B. It opens Ca2+ channels that are embedded in the ER membrane, allowing Ca2+ to enter the cytosol.
C. It generates a hole in the endoplasmic reticulum (ER), through which Ca2+ can enter the cytosol.
D. It directly activates phospholipase C (PLC).
E. It directly activates protein kinase C (PKC).

Answer 1

IP3 functions by binding to ligand-gated calcium channels in the ER membrane, releasing Ca²+ into the cytosol, which is crucial for activating various cellular processes.

Step-by-step explanation:

In the inositol phospholipid pathway, inositol triphosphate (IP3) functions by binding to ligand-gated calcium channels in the endoplasmic reticulum (ER) membrane. This action allows stored Ca²+ to be released into the cytosol. Consequently, these calcium ions go on to activate several other cellular processes, including enzymatic functions through direct binding or interaction with calcium-binding proteins like calmodulin.

As a specific answer to the question, IP3 opens Ca²+ channels that are embedded in the ER membrane, allowing Ca²+ to enter the cytosol (Option B). It is important to note that IP3 does not produce DAG, generate holes in the ER, directly activate phospholipase C (PLC), nor directly activate protein kinase C (PKC). Those functions are associated with different molecules or steps within the pathway.