Interaction of tubulin with guanosine 5'-O-(1-thiotriphosphate) diastereoisomers: specificity of the alpha-phosphate binding region.
Interaction of tubulin with guanosine 5'-O-(1-thiotriphosphate) diastereoisomers: specificity of the alpha-phosphate binding region.
复制标题
微管蛋白与鸟苷 5-O-(1-硫代三磷酸) 非对映异构体的相互作用：α-磷酸结合区域的特异性。
DOI：
10.1021/bi00205a026
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发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
Gaskin,F
中科院分区：
文献类型：
--
作者：
Xu,S;Gaskin,F
Revised Manuscript Received July 26, 1994® abstract: The exchangeable nucleotide-binding site of tubulin has been studied using diastereoisomers A (Sp) and B (Rp) of guanosine 5'-0-(l-thiotriphosphate)(GTPaS) in which the phosphorus atomto which sulfur is attached is chiral. GTPaS (A)(10 µ) nucleated assembly of purified tubulin (20 µ) into microtubules in buffer containing 0.1 M 2-(7V-morpholino) ethanesulfonic acid with 3 mM Mg2+ and 1 mM EGTA, pH 6.6 at 37 C. With 0.2 mM GTPaS (A), the critical concentration (Cc; minimum protein concentration required for assembly) was 8 µ tubulin. Neither 0.2 mM GTP nor GTPaS (B) promoted microtubule assembly inbuffer with 0.5-6.75 mM Mg2+ and 20-70 µ tubulin. The Ccvalues for GTPaS-(A)-induced assembly of tubulin in buffer with 30% glycerol and of microtubule protein (tubulin and microtubule-associated proteins) in buffer were lower than for GTP. GTPaS (A)-induced microtubules were more stable to the cold and to Ca2+. GTPaS (A) and GTP but not GTPaS (B) bound tightly to tubulin at 4 C. Although GTPaS (B) did not nucleate assembly, it did bind to tubulin since it was incorporated into the growingmicrotubule. Both isomers were hydrolyzed in the microtubules. These studies show that GTPaS (A) promotes tubulin assembly better thanGTP and GTPaS (B) and that there is stereoselectivity at the-phosphate binding region of tubulin. The stereoselectivity may be dueto different MgGTPaS (A) and-(B) interactions with tubulin.
