Type II regulatory subunits are not required for the anchoring-dependent modulation of Ca2+ channel activity by cAMP-dependent protein kinase
Type II regulatory subunits are not required for the anchoring-dependent modulation of Ca2+ channel activity by cAMP-dependent protein kinase
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DOI：
10.1073/pnas.94.20.11067
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发表时间：
1997-09-30
影响因子：
11.1
通讯作者：
McKnight, GS
中科院分区：
文献类型：
--
作者：
Burton, KA;Johnson, BD;McKnight, GS
camp依赖性蛋白激酶（PKA）对特定蛋白的优先磷酸化可能部分是由PKA锚定在靠近靶蛋白的a激酶锚定蛋白（AKAPs）家族上介导的，这种相互作用被认为依赖于II型调节（RII）亚基与AKAPs的结合，并且对于PKA依赖的α -氨基-3-羟基-5-甲基-4-异唑丙酸/海因酸盐受体、l型Ca2+通道、我们假设，对无处不在表达的RII α亚基基因的靶向破坏将揭示那些需要锚定PKA的组织和信号事件，RII α敲除小鼠表现正常和健康，在成人骨骼肌中，RI α蛋白水平升高，部分补偿了RII α的损失，尽管如此，观察到催化(C)亚基蛋白水平和总激酶活性的降低，令人惊讶的是，与野生型相比，RII α敲除骨骼肌中l型Ca2+通道的锚定pka依赖性增强没有变化，尽管它对PKA-AKAP相互作用的抑制剂更敏感。在野生型骨骼肌中，C亚基与横小管中的l型Ca2+通道共定位，并在敲除肌肉中保持这种定位。RI α亚基被证明可以结合AKAPs，尽管其亲和力比RII α亚基低500倍。RII α敲除小鼠骨骼肌中l型Ca2+通道的增强表明，尽管对AKAP结合的亲和力较低，但RI α能够进行生理相关的锚定相互作用。
Preferential phosphorylation of specific proteins by cAMP-dependent protein kinase (PKA) may be mediated in part by the anchoring of PKA to a family of A-kinase anchor proteins (AKAPs) positioned in close proximity to target proteins, This interaction is thought to depend on binding of the type II regulatory (RII) subunits to AKAPs and is essential for PKA-dependent modulation of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate receptor, the L-type Ca2+ channel, and the K-Ca channel, We hypothesized that the targeted disruption of the gene for the ubiquitously expressed RII alpha subunit would reveal those tissues and signaling events that require anchored PKA, RII alpha knockout mice appear normal and healthy, In adult skeletal muscle, RI alpha protein levels increased to partially compensate for the loss of RII alpha, Nonetheless, a reduction in both catalytic (C) subunit protein levels and total kinase activity was observed, Surprisingly, the anchored PKA-dependent potentiation of the L-type Ca2+ channel in RII alpha knockout skeletal muscle was unchanged compared with wild type although it was more sensitive to inhibitors of PKA-AKAP interactions, The C subunit colocalized with the L-type Ca2+ channel in transverse tubules in wild-type skeletal muscle and retained this localization in knockout muscle, The RI alpha subunit was shown to bind AKAPs, although with a 500-fold lower affinity than the RII alpha subunit, The potentiation of the L-type Ca2+ channel in RII alpha knockout mouse skeletal muscle suggests that, despite a lower affinity for AKAP binding, RI alpha is capable of physiologically relevant anchoring interactions.