Does PKA activates phosphorylase kinase?
Does PKA activates phosphorylase kinase? The enzyme catalyzing the activation of phosphorylase kinase is protein kinase A (PKA), which is switched on by a second messenger, cyclic AMP (Sections 10.4. 2 and 15.1. 5). As will be discussed, hormones such as epinephrine induce the breakdown of glycogen by activating a cyclic AMP cascade (Figure 21.13). Does PKA inhibit glycogen synthesis? Glycogen synthase kinase 3 (GSK-3), a ubiquitously expressed and evolutionarily conserved protein serine/threonine kinase, was originally identified as an enzyme that regulates glycogen synthesis in response to insulin (1). PKA physically associates with, phosphorylates, and inactivates both isoforms of GSK-3....