Actin interacting protein 1 (Aip1) is a conserved component of the actin cytoskeleton first identified in a two-hybrid screen against yeast actin. Here, we report that Aip1p also interacts with the ubiquitous actin depolymerizing factor cofilin. A two-hybrid–based approach using cofilin and actin mutants identified residues necessary for the interaction of actin, cofilin, and Aip1p in an apparent ternary complex. Deletion of the AIP1 gene is lethal in combination with cofilin mutants or act1-159, an actin mutation that slows the rate of actin filament disassembly in vivo. Aip1p localizes to cortical actin patches in yeast cells, and this localization is disrupted by specific actin and cofilin mutations. Further, Aip1p is required to restrict cofilin localization to cortical patches. Finally, biochemical analyses show that Aip1p causes net depolymerization of actin filaments only in the presence of cofilin and that cofilin enhances binding of Aip1p to actin filaments. We conclude that Aip1p is a cofilin-associated protein that enhances the filament disassembly activity of cofilin and restricts cofilin localization to cortical actin patches.
Aip1p Interacts with Cofilin to Disassemble Actin Filaments
Address correspondence to David C. Amberg, State University of New York Health Science Center, Department of Biochemistry and Molecular Biology, Syracuse, NY 13210. Tel.: (315) 464-8727. Fax: (315) 464-8750. E-mail: [email protected]
Research in D.C. Amberg's laboratory was supported by National Institutes of Health (NIH) grant GM56189. Research in D.G. Drubin's laboratory was supported by NIH grant GM42759 and A.A. Rodal was supported by a Howard Hughes Medical Institute Predoctoral Fellowship.
Avital A. Rodal, Jonathan W. Tetreault, Pekka Lappalainen, David G. Drubin, David C. Amberg; Aip1p Interacts with Cofilin to Disassemble Actin Filaments . J Cell Biol 14 June 1999; 145 (6): 1251–1264. doi: https://doi.org/10.1083/jcb.145.6.1251
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