The Abl-related gene (Arg) nonreceptor tyrosine kinase uses two F-actin-binding domains to bundle F-actin.
Abl family nonreceptor tyrosine kinases regulate cellular morphogenesis and motility through functional interactions with the actin cytoskeleton. Although Abl family kinases are known to contain filamentous (F)-actin-binding domains at their C termini, it is unclear how Abl family kinases regulate the structure and/or function of the actin cytoskeleton. We show here that the Abl-related kinase Arg binds with positive cooperativity to F-actin in vitro with binding saturating at a ratio of one Arg/two actin molecules. Measurements of the F-actin-binding properties of Arg deletion mutants led to the identification of a second, previously uncharacterized internal F-actin-binding domain in Arg. Purified Arg can bundle F-actin in vitro, and this bundling activity requires both F-actin-binding domains. An Arg-yellow fluorescent protein fusion protein can induce the formation of actin-rich structures at the lamellipodia of Swiss 3T3 fibroblasts. Both of Arg's F-actin-binding domains are necessary and sufficient for the formation of these actin-rich structures. Together, our data suggest that Arg can use its F-actin-bundling activity to directly regulate actin cytoskeletal structure in vivo.
Wang
Y
Y
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Miller
A L
AL
Mooseker
M S
MS
Koleske
A J
AJ
D016475:3T3 Cells; D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D051379:Mice; D008854:Microscopy, Electron; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D000199:Actins; D011993:Recombinant Fusion Proteins; C426236:ARG tyrosine kinase; D011505:Protein-Tyrosine Kinases