Going in GTP cycles in the nucleolus - PubMed (original) (raw)

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Going in GTP cycles in the nucleolus

Tom Misteli. J Cell Biol. 2005.

Abstract

Proteins are directed to cellular compartments by specific localization signals. A GTP-driven cycle has now been identified as a mechanism for protein targeting to the nucleolus. The involvement of a GTP switch suggests that nucleolar localization can be regulated and may be responsive to extracellular stimuli via signaling pathways. The uncovered mechanism also implies that localization is determined by increased retention rather than directed targeting.

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Figure 1.

Figure 1.

Nucleolar localization by GTP-dependent retention. (Left) In the absence of GTP binding, nucleostemin diffuses rapidly through the nucleolus. (Right) Upon binding of GTP, the inhibitory action of the inhibitory domain (I) is relieved. As nucleostemin diffuses through the nucleolus, the basic domain (B) is able to undergo lasting interactions with nucleolar components. Nucleostemin accumulates in the nucleolus due to its prolonged retention. Exchange of GTP reverses the stable binding, and nucleostemin dissociates from the nucleolus. Signaling pathways may affect the availability of the protein for nucleolar import and/or its retention.

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References

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