Figure 7-58. Some ways in which the activity of gene regulatory proteins is regulated in eucaryotic cells.

Figure 7-58Some ways in which the activity of gene regulatory proteins is regulated in eucaryotic cells

(A) The protein is synthesized only when needed and is rapidly degraded by proteolysis so that it does not accumulate. (B) Activation by ligand binding. (C) Activation by phosphorylation. (D) Formation of a complex between a DNA-binding protein and a separate protein with a transcription-activating domain. (E) Unmasking of an activation domain by the phosphorylation of an inhibitor protein. (F) Stimulation of nuclear entry by removal of an inhibitory protein that otherwise keeps the regulatory protein from entering the nucleus. (G) Release of a gene regulatory protein from a membrane bilayer by regulated proteolysis.

Each of these mechanisms is typically controlled by extracellular signals which are communicated across the plasma membrane to the gene regulatory proteins in the cell. The ways in which this signaling occurs is discussed in Chapter 15. Mechanisms (A)-(F) are readily reversible and therefore also provide the means to selectively inactivate gene regulatory proteins.

From: How Genetic Switches Work

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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