Figure 7-98. Three mechanisms for the localization of mRNAs.

Figure 7-98Three mechanisms for the localization of mRNAs

The mRNA to be localized leaves the nucleus through nuclear pores (top). Some localized mRNAs (left diagram) travel to their destination by associating with cytoskeleton motors (green). As described in Chapter 16, these motors use the energy of ATP hydrolysis to move unidirectionally along components of the cytoskeleton. At their destination, the mRNAs are held in place by anchor proteins (black). Other mRNAs randomly diffuse through the cytosol and are simply trapped and therefore concentrated at their sites of localization (center diagram). Still other mRNAs (right diagram) are degraded in the cytosol unless they have bound, through random diffusion, a localized protein complex that anchors and protects the mRNA from degradation (black). Each of these mechanisms requires specific signals on the mRNA, which are typically located in the 3′ UTR (see Figure 7-99). In many cases of mRNA localization, additional mechanisms block the translation of the mRNA until it is properly localized. (Adapted from H.D. Lipshitz and C.A. Smibert, Curr. Opin. Gen. Dev. 10:476–488, 2000.)

From: Posttranscriptional Controls

Cover of Molecular Biology of the Cell
Molecular Biology of the Cell. 4th edition.
Alberts B, Johnson A, Lewis J, et al.
New York: Garland Science; 2002.
Copyright © 2002, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter; Copyright © 1983, 1989, 1994, Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson .

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