All are second messengers except:: (A) Cyclic AMP, (B) Guanylyl cyclase, (C) Diacylglycerol, (D) Inositol triphosphate
Answer is B. Remember that guanylyl cyclase is an enzyme while cGMP is a secondary messenger
Types of second messengers
There are 3 basic types of secondary messenger molecules:
1. Hydrophobic

DAG
IP3
Phosphotidylinositol

2. Hydrophilic

cAMP
cGMP

3. Gases

NO
CO