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：1990
卷号：87
期号：18
页码：6954-6958
DOI：10.1073/pnas.87.18.6954
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The yeast repressor alpha 2 is shown, by analysis of deletion-bearing alpha 2-beta-galactosidase hybrid proteins, to have two structurally distinct nuclear localization signals. The cellular location of hybrid proteins was determined by indirect immunofluorescence and optical sectioning of whole fixed yeast cells. The two nuclear localization signals are far apart in the alpha 2 primary structure and do not have any sequence homology. One signal is, as reported previously, within the aminoterminal 13 amino acids of alpha 2. Deletion of only this aminoterminal signal has no evident effect on nuclear localization. The second signal is in a central portion of alpha 2, within the alpha 2 homeodomain. Since this signal is within the amino terminus of the alpha 2 homeodomain, the homeodomain mediates nuclear localization in addition to, and independently of, DNA binding. Deletion of only this second signal results in inefficient localization and accumulation of mutant protein at discrete sites on the nuclear envelope assumed to be nuclear pores. We propose that the two signals in alpha 2 are functionally distinct and act at different steps in a localization pathway.
