Open AccessThe I/LWEQ module: a conserved sequence that signifies F-actin binding in functionally diverse proteins from yeast to mammals
Author(s) -
Richard O. McCann,
Susan W. Craig
Publication year - 1997
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.94.11.5679
Subject(s) - biology , actin , actin cytoskeleton , microbiology and biotechnology , actin binding protein , conserved sequence , saccharomyces cerevisiae , peptide sequence , cytoskeleton , yeast , biochemistry , cell , gene
Talin is an actin-binding protein involved in integrin-mediated cell adhesion and spreading. The C-terminal 197 amino acids of vertebrate talin are 45% similar to the C-terminal residues of Sla2, a yeast protein implicated in polarized assembly of the yeast actin cytoskeleton. Talin is also homologous in this region to nematode talin, cellular slime mold filopodin, and an Sla2 homolog from nematode. Analysis of the conserved C-terminal sequences of these five proteins withblock maker reveals a series of four blocks, which we name the I/LWEQ module after the conserved initial residues in each block. Experiments presented here show that the conserved protein domain represented by the I/LWEQ module competes quantitatively with native talin for binding to F-actinin vitro . Furthermore, the corresponding domain of Sla2 binds to both yeast and vertebrate F-actinin vitro . Mutation of one of the conserved residues in the fourth conserved block abolishes the interaction of the Sla2 I/LWEQ module with F-actin. These results establish the location of an F-actin binding domain in native talin, demonstrate that direct interaction of Sla2 with actin is a possible basis for its effect on the actin cytoskeletonin vivo , and define the I/LWEQ consensus as a new actin-binding motif.