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Chapter category: Cell Metabolism
A Common Binding Site for Actin-Binding Proteins on the Actin Surface
Chapter authors:
Roberto Dominguez
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The dynamic remodeling of the actin cytoskeleton plays an essential role in many
cellular processes, including cell motility, cytokinesis, and intracellular transport. A
large number of actin-binding proteins (ABPs) participate in this process, regulating the assembly of actin filaments into functional networks. ABPs are extremely diverse, both structurally and functionally, but they most seem to share a common binding area on the actin surface, consistent of the cleft between actin subdomains 1 and 3. Actin itself is thought to interact in this cleft in the filament. As a result, part of the cleft becomes buried in F-actin by inter-subunit contacts, whereas another part remains exposed and mediates the interactions of various filamentous actin-binding proteins. The convergence of actin-binding proteins into a common binding area imposes enormous constraints on their interactions and could serve a regulatory function. Because the cleft falls near the hinge for domain motions in actin, binding in this area is an effective way for ABPs to “sense” the conformation of actin, in particular conformational changes resulting from ATP hydrolysis by actin or from the G- to F-actin transition.
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