Protein Kinase A Anchoring

Specificity is perhaps the most enigmatic property of hormone-mediated signaling pathways, especially when one considers that more than 30 hormones employ the ubiquitous second messengers, Ca2+, phospholipid, or cAMP, to relay messages from the cell membrane to intracellular effectors. In most cases the net signaling effect is to activate protein kinases or phosphoprotein phosphatases, which, in turn, alter the phosphorylation state of cellular target proteins. Although both enzyme classes have been intensely researched since the late 1950s, it is still unclear how individual hormones activate the correct pool of kinase or phosphatase to trigger specific intracellular events.