Considerations on the Mechanism of Nuclear Protein Localization in Yeast
The past ten years have witnessed tremendous advances in an understanding of how proteins are selectively localized to organelles or the cell exterior (1–5). However, the mechanism by which specific proteins accumulate in the nucleus is relatively poorly understood (6). Until recently, the commonly accepted model for nuclear protein localization has been that all proteins freely diffuse into the nucleus with subsequent retention of nuclear proteins by binding to a non-diffusible substrate (e.g., DNA) (7). The general acceptance of this model is perhaps responsible for the tardiness of recent observations which indicate that nuclear localization may involve more than simple diffusion. A second model, for which evidence is now emerging, is that proteins are selectively translocated across the nuclear envelope. This second model is based on observations that nuclear proteins contain a determinant which identifies them as proteins destined to be taken into the nucleus (8–12). Here I briefly review one such observation.
KeywordsMigration Proline Saccharomyces Clarification Chromato
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