蛋白激酶B及其在磷脂酰肌醇3-激酶介导的信号转导中的作用

蛋白激酶Ｂ（ＰＫＢ）是原癌基因ｃ－ａｋｔ的表达产物，它参与由生长因子激活的经磷脂磷肌醇３－激酶（ＰＩ３Ｋ）介导的信号转导过程。与许多蛋白激酶相似，ＰＫＢ分子具有一特殊的ＡＨ／ＰＨ结构域（ＡＨ／ＰＨｄｏｍａｉｎ），后者能介导信号分子间的相互作用。ＰＫＢ是ＰＩ３Ｋ直接的靶蛋白。ＰＩ３Ｋ产生的脂类第二信使ＰＩ－３，４，Ｐ２和ＰＩ－３，４，５－Ｐ３等均能与ＰＫＢ和磷酸肌醇依赖性蛋白激酶（ＰＤＫ）的ＡＨ／Ｐ

Protein kinase B and its role in the signal transduction pathway mediated by phosphoinositide 3-kinase

Protein kinase B (PKB) is the expression product of a proto oncongen (c akt), which is involved in the signaling pathways initiated by some growth factors and mediated by phosphoinositide 3 kinase ( PI3K).PKB is a direct target of PI3K. Similar to many protein kinases, PKB has a specific AH/PH domain which can mediate the interaction between signaling molecules. The lipid second messengers, PI 3,4 P 2 and PI 3,4,5 P 3 produced by PI3K, can bind to the AH/PH domain of PKB and of PDK (phosphoinositide dependent protein kinase ). This binding translocates PKB and PDK to the plasma membrane, and activates them. PKB is also activated via phosphorylation by PDK and, in turn, will activate the anti apoptotic machinery, glucose metabolism ( glycogen synthesis, glycolysis and glucose uptake ) and protein synthesis. All these lead to cell growth and proliferation.