期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：7
页码：2820-2824
DOI：10.1073/pnas.88.7.2820
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Ultraviolet irradiation of the [3H]colchicine-tubulin complex leads to direct photolabeling of tubulin with low but practicable efficiency. The bulk (70% to greater than 90%) of the labeling occurs on beta-tubulin and appears early after irradiation, whereas alpha-tubulin is labeled later. The labeling ratio of beta-tubulin to alpha-tubulin (beta/alpha ratio) is reduced by prolonged incubation, prolonged irradiation, urea, high ionic strength, the use of aged tubulin, dilution of tubulin, or large concentrations of colchicine or podophyllotoxin. Glycerol increases the beta/alpha ratio. Limited data with [3H]podophyllotoxin show that it covalently bound with a similar beta/alpha distribution. Vinblastine, on the other hand, exhibits preferential attachment to alpha-tubulin. The possibilities that colchicine binds at the interface between alpha-tubulin and beta-tubulin, that the drug spans this interface, and that both subunits may contribute to the binding site are suggested.
