What are the types of second messengers?

Types of second messengers include: cAMP, cGMP, calcium ions, diacylglycerol, and IP3. cAMP and cGMP, which serve as second messengers in both ion-channel and hormone signaling in eukaryotes. Adenylyl cyclase converts ATP into cAMP by removing two phosphate groups from ATP. cGMP is produced from GTP through the enzyme guanylyl cyclase. Both of these cyclic nucleotides can bind to different classes of targets. The most common targets are protein kinases. cAMP binds to protein kinase A, and cGMP binds to protein kinase G. Calcium ions are the most common second messenger in neurons. Information is transmitted by a rise in the cytoplasmic calcium concentration, which allows for Ca2+ to bind to a large number of Ca2+ binding proteins. IP3 is generated from the hydrolysis of PIP2 by the enzyme phospholipase C. IP3 acts by releasing calcium ions from stores such as from the ER. In contrast, diacylglycerol remains in the membrane and activates protein kinase C.