Effect of cyclic nucleotide analogs on intrachain site I of protein kinase isozymes.
Effect of cyclic nucleotide analogs on intrachain site I of protein kinase isozymes.
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环核苷酸类似物对蛋白激酶同工酶链内位点 I 的影响。
DOI：
10.1111/j.1432-1033.1982.tb06677.x
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
Miller,JP
中科院分区：
文献类型：
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作者：
Corbin,JD;Rannels,SR;Flockhart,DA;Robinson-Steiner,AM;Tigani,MC;Døskeland,SO;Suva,RH;Suva,R;Miller,JP
分析了[~3H]cAMP结合反应中存在的众多cAMP类似物对[~3H]cAMP随后从cAMP依赖的蛋白激酶I和I1调节亚基上解离的影响。某些经过C-8或C-2修饰的类似物对两种同工酶的两个链内cAMP结合位点中的一个(位点1)显示出相对的选择性。C-6上的修饰导致了第二个位置(位置2)的选择性。结合位点I和位点Z的类似物抑制[~3H]cAMP结合比单独使用类似物强得多。总体而言，位点1的选择性与类似物刺激选择位点2的[~3H]ClMP结合的能力之间存在相关性。位点1定向的类似物刺激了[~3H]CIMP结合的初始速率。这种刺激作用在组蛋白等聚阳离子蛋白存在时被增强，而被高离子强度抑制。I型和II型同工酶对这一效应的模拟特异性表现出很大的差异。对于第一类类似物，刺激[~3H]CIMP结合最有效的是那些含有C-8上的氮原子的类似物，8-氨基丁氨基-cAMP是最有效的。I1型对C-8上含硫原子的类似物反应最好，8-SH-cAMP是受试者中最有效的。当使用I型酶时，有MgATP存在时刺激作用增强，而使用II型时，这种核苷酸没有作用。在完整的组织中，cAMP与任何一种同工酶的第一位点结合都能刺激与第二位点的结合。
The effects of numerous cAMP analogs present in the [3H]cAMP binding reaction on subsequent dissociation of [3H]cAMP from the regulatory subunit of CAMP‐dependent protein kinase I and I1 were analyzed. Certain analogs with modification at either C‐8 or C‐2 showed relative selectivity for one (site 1) of two intrachain cAMP binding sites of both isozymes. Modification at C‐6 caused selectivity for the second site (site 2). The combination of a site‐I‐directed and site‐Zdirected analog inhibited [3H]cAMP binding much more than did either analog alone. In general, there was a correlation between the site 1 selectivity and the ability of the analog to stimulate the binding of [3H]clMP, which selects site 2. The site‐1‐directed analogs stimulated the initial rate of [3H]cIMP binding. The stimulatory effect was enhanced in the presence of a polycationic protein such as histone and was inhibited by high ionic strength. The type I and II isozymes exhibited large differences in analog specificity for this effect. For type I, of the analogs tested the most efficacious for stimulating [3H]cIMP binding were those containing a nitrogen atom attached to C‐8, 8‐aminobutylamino‐CAMP being the most effective. Type I1 responded best to analogs con‐ taining a sulfur atom attached to C‐8, 8‐SH‐CAMP being the most effective of those tested. The stimulatory effect was accentuated in the presence of MgATP when using type I, but this nucleotide had no effect when using type II. It is proposed that in intact tissues cAMP binding to site 1 of either isozyme stimulates the binding to site 2.