Role of Formins in Actin Assembly: Nucleation and Barbed-End Association

David Pruyne(Cornell University), Marie Evangelista(Queen's University), Changsong Yang(University of Pennsylvania), Erfei Bi(University of Pennsylvania), Sally H. Zigmond(University of Pennsylvania), Anthony Bretscher(Cornell University), Charles Boone(University of Toronto)
Science
July 26, 2002
Cited by 749

Abstract

Nucleation of branched actin filaments by the Arp2/3 complex is a conserved process in eukaryotic cells, yet the source of unbranched actin filaments has remained obscure. In yeast, formins stimulate assembly of actin cables independently of Arp2/3. Here, the conserved core of formin homology domains 1 and 2 of Bni1p (Bni1pFH1FH2) was found to nucleate unbranched actin filaments in vitro. Bni1pFH2 provided the minimal region sufficient for nucleation. Unique among actin nucleators, Bni1pFH1FH2 remained associated with the growing barbed ends of filaments. This combination of properties suggests a direct role for formins in regulating nucleation and polarization of unbranched filamentous actin structures.


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