Cell Biology

Regulating Interfacial Interactions

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Science  12 May 2000:
Vol. 288, Issue 5468, pp. 929
DOI: 10.1126/science.288.5468.929c

The ezrin-radixin-moesin (ERM) protein family regulates crosslinking of the membrane and cytoskeleton and is important in actin-rich cell surface structures such as microvilli. Function is regulated by an intramolecular association between the N-terminal FERM domain—a common membrane binding module—and the C-terminal F-actin binding domain.

Pearson et al. determined the structure of a complex of the FERM and tail domains of moesin. The tail binds in an extended conformation over a large area of the FERM surface. Phosphorylation destabilizes the interaction, and the free tail is likely to bind to actin in a distinct conformation.

Similar conformational plasticity was recently observed by Kim et al. for the Wiskott-Aldrich syndrome protein (WASP) which also is involved in regulation of the actin cytoskeleton. The GTPase-binding domain (GBD) of WASP is stabilized by interaction with the C-terminal region, and this prevents the C-terminal region from enhancing actin nucleation. Binding of the GTPase CDC42 to the GBD disrupts its hydrophobic core and abolishes the intramolecular interaction. This intramolecular interface also may be modulated by phosphorylation.—VV

Cell101, 259 (2000); Nature404, 151 (2000)

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