GTP水解与微管蛋白聚合的化学计量学
Stoichiometry of GTP hydrolysis and tubulin polymerization.
作者信息
Maccioni R, Seeds N W
出版信息
Proc Natl Acad Sci U S A. 1977 Feb;74(2):462-6. doi: 10.1073/pnas.74.2.462.
Microtubule formation from lamb brain tubulin isolated by affinity chromatography and freed of exchangeable nucleotide requires GTP for maximal rate and extent of polymerization. The nucleotide analogs guanylylmethylenediphosphate and guanylylimidodiphosphate fail to replace GTP; in addition, neither the presence of microtubule associated proteins nor 5 M glycerol relieves the GTP requirement. The relation of GTP concentration and microtubule formation shows an association constant K = 1 X 10(4) M-1; furthermore, GDP and guanylylimidodiphosphate are competitive inhibitors of GTP for polymerization. Using a rapid filter assay for microtubule formation that allows the quantitative analysis of early polymerization kinetics and correcting for GTP hydrolysis uncoupled from tubulin polymerization, a stoichiometry of two molecules of GTP hydrolyzed per mole of tubulin dimer incorporated into microtubules has been found.
通过亲和层析法从羊脑微管蛋白中分离并去除可交换核苷酸后形成微管，其聚合的最大速率和程度需要GTP。核苷酸类似物鸟苷基亚甲基二磷酸和鸟苷亚氨基二磷酸不能替代GTP；此外，微管相关蛋白的存在或5M甘油都不能消除对GTP的需求。GTP浓度与微管形成的关系显示结合常数K = 1×10⁴ M⁻¹；此外，GDP和鸟苷亚氨基二磷酸是GTP聚合的竞争性抑制剂。使用一种用于微管形成的快速过滤测定法，该方法允许对早期聚合动力学进行定量分析，并校正与微管蛋白聚合解偶联的GTP水解，已发现每摩尔掺入微管的微管蛋白二聚体水解两分子GTP的化学计量关系。
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