IκB激酶的激活及其在NF-κB活化过程中的作用

Activation of IκB Kinase and Its Effect in the Course of NF-κB Activation

在NF κB二聚体活化过程中 ,IκB激酶 (IKK)通过对抑制性蛋白κB (IκBs)的磷酸化而扮演关键的角色 .IKK复合物在胞浆内有多种存在形式 ,其中 ,IKK α、IKK β两者氨基酸序列 5 2 %的同源性 ,空间构象相似 ,常为催化亚单位 ,而IKK γ则为调节亚单位 ,它们以不同的方式活化IκBs.核因子κB诱导激酶 (NIK)与丝裂原活化蛋白激酶激酶激酶 1(MEKK1)均为IKK的上游激酶 ,NIK可引起IKK αSer176、IKK β相应位点的磷酸化 ,而MEKK1主要引起IKK β的活化 .通过级联反应 ,使IκBs磷酸化而与NF κB解离 ,致使NF κB被激活并易位入核 。

During the course of NF κB dimer activation, IκB kinase(IKK) play a crucial role by phosphorylation of inhibitory κB(IκBs). There are lots of existing forms in cytoplasm about IKK complex, which activate IκBs through different ways. Generally, IKK has two catalytic subunits, IKK α?IKK β, which have 52% amino acids identity and similar construction, one regulatory subunit, IKK γ. Both NF κB inducing kinase(NIK) and mitogen activated protein kinase kinase kinase 1(MEKK 1) are upstream kinases of IKK. MEKK 1 preferentially activates IKK β,whereas NIK efficiently phosphorylates both IKK α Ser176 and IKK β. Through cascade reaction, IκBs are phosphorylated by IKK and dissociated from IκB NF κB complex, NF κB dimer enter the nucleus and activate a series of genes.