Stereochemistry of the guanyl nucleotide binding site of transducin probed by phosphorothioate analogues of GTP and GDP.
Stereochemistry of the guanyl nucleotide binding site of transducin probed by phosphorothioate analogues of GTP and GDP.
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通过 GTP 和 GDP 的硫代磷酸酯类似物探测转导蛋白的鸟苷酸结合位点的立体化学。
作者：
G. Yamanaka;F. Eckstein;L. Stryer
牛视网膜杆外节transducin鸟苷酸结合位点的立体化学与GTP和GDP的硫代磷酸酯类似物探测。转导蛋白对GTP的五种硫代类似物具有显著不同的亲和力，如通过它们抑制GTP酶活性、与GTP竞争进入转导蛋白和置换与转导蛋白结合的GDP的有效性所测量的。结合亲和力的顺序是GTP γ S =（Sp）-GTP α S大于（Rp）-GTP α S大于（Sp）-GTP β S远大于（Rp）-GTP β S。转导素对GTP γ S的亲和力比对（Rp）-GTP β S的亲和力高10（4）以上。这五种类似物在引起转导素从膜释放和激活磷酸二酯酶方面具有相同的相对效力。转导蛋白水解（Sp）-GTP α S的l/e时间为55 s，而GTP为28 s。相反，（Rp）-GTP α S，如GTP γ S，在几小时的时间尺度上不水解。GDP的硫代类似物置换结合GDP的有效性顺序为（Sp）-GDP α S大于GDP大于（Rp）-GDP α S大于GDP β S。转导素对（Sp）-GDP α S的亲和力比对GDP β S的亲和力高约10倍。Mg ~（2+）是GTP和GDP与transducin结合所必需的。Cd 2+不会导致GTP的α-或β-磷原子的立体特异性逆转。这些结果导致以下结论：GTP的α-磷上的pro-R氧原子不结合Mg 2+，而是与蛋白质相互作用。在α-磷的pro-S氧似乎并不参与与转导蛋白的关键相互作用。（250字处删节）
The stereochemistry of the guanyl nucleotide binding site of transducin from bovine retinal rod outer segments was probed with phosphorothioate analogues of GTP and GDP. Transducin has markedly different affinities for the five thio analogues of GTP, as measured by their effectiveness in inhibiting GTPase activity, competing with GTP for entry into transducin, and displacing GDP bound to transducin. The order of binding affinities is GTP gamma S = (Sp)-GTP alpha S greater than (Rp)-GTP alpha S greater than (Sp)-GTP beta S much greater than (Rp)-GTP beta S. The affinity of transducin for GTP gamma S is greater than 10(4) higher than that for (Rp)-GTP beta S. These five analogues have the same relative potencies in eliciting the release of transducin from the membrane and in activating the phosphodiesterase. Transducin hydrolyzes (Sp)-GTP alpha S with a l/e time of 55 s, compared with 28 s for GTP. In contrast, (Rp)-GTP alpha S, like GTP gamma S, is not hydrolyzed on the time scale of several hours. The order of effectiveness of thio analogues of GDP in displacing bound GDP is (Sp)-GDP alpha S greater than GDP greater than (Rp)-GDP alpha S greater than GDP beta S. The affinity of transducin for (Sp)-GDP alpha S is about 10-fold higher than that for GDP beta S. Mg2+ is required for the binding of GTP and GDP to transducin. Cd2+ does not lead to a reversal of stereospecificity at either the alpha- or beta-phosphorus atom of GTP. These results lead to the following conclusions: The pro-R oxygen atom at the alpha-phosphorus of GTP does not bind Mg2+ but instead interacts with the protein. The pro-S oxygen at the alpha-phosphorus does not appear to be involved in a critical interaction with transducin.(ABSTRACT TRUNCATED AT 250 WORDS)
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杆外段环GMP磷酸二酯酶的激活机制。
DOI：
--
发表时间：
1983
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Yamazaki,A;Stein,PJ;Chernoff,N;Bitensky,MW
通讯作者：
Bitensky,MW
牛视网膜杆外节转导蛋白的表征。
DOI：
--
发表时间：
1983
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Fung,BK
通讯作者：
Fung,BK
棒盘膜 cGMP 磷酸二酯酶及其控制酶的实时测定。
影响因子：
--
作者：
Liebman,PA;Evanczuk,AT
通讯作者：
Evanczuk,AT
DOI：
--
发表时间：
1983
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Fung,BK;Nash,CR
通讯作者：
Nash,CR
从 cDNA 序列推导的转导蛋白 α 亚基的氨基酸序列。
DOI：
10.1073/pnas.82.13.4311
发表时间：
1985
影响因子：
11.1
作者：
Medynski,DC;Sullivan,K;Smith,D;VanDop,C;Chang,FH;Fung,BK;Seeburg,PH;Bourne,HR
通讯作者：
Bourne,HR