Arabidopsis BRICK1/HSPC300 is an essential WAVE-complex subunit that selectively stabilizes the Arp2/3 activator SCAR2

Curr Biol. 2006 May 9;16(9):895-901. doi: 10.1016/j.cub.2006.03.061. Epub 2006 Apr 6.


The actin cytoskeleton dynamically reorganizes the cytoplasm during cell morphogenesis. The actin-related protein (Arp)2/3 complex is a potent nucleator of actin filaments that controls a variety of endomembrane functions including the endocytic internalization of plasma membrane , vacuole biogenesis , plasma-membrane protrusion in crawling cells , and membrane trafficking from the Golgi . Therefore, Arp2/3 is an important signaling target during morphogenesis. The evolutionarily conserved Rac-WAVE-Arp2/3 pathway links actin filament nucleation to cell morphogenesis . WAVE translates Rac-GTP signals into Arp2/3 activation by regulating the stability and/or localization of the activator subunit Scar/WAVE . The WAVE complex includes Sra1/PIR121/CYFIP1, Nap1/NAP125, Abi-1/Abi-2, Brick1(Brk1)/HSPC300, and Scar/WAVE : Defining the in vivo function of each subunit is an important step toward understanding this complicated signaling pathway. Brk1/HSPC300 has been the most recalcitrant WAVE-complex protein and has no known function. In this paper, we report that Arabidopsis brick1 (brk1) is a member of the "distorted group" of trichome morphology mutants, a group that defines a WAVE-ARP2/3 morphogenesis pathway . In this paper we provide the first strong genetic and biochemical evidence that BRK1 is a critical WAVE-complex subunit that selectively stabilizes the Arp2/3 activator SCAR2.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actin-Related Protein 2-3 Complex / metabolism*
  • Amino Acid Sequence
  • Arabidopsis / growth & development*
  • Arabidopsis / ultrastructure
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Arabidopsis Proteins / physiology*
  • Molecular Sequence Data
  • Mutation
  • Plant Leaves / ultrastructure
  • Sequence Homology, Amino Acid
  • Wiskott-Aldrich Syndrome Protein Family*


  • Actin-Related Protein 2-3 Complex
  • Arabidopsis Proteins
  • BRK1 protein, Arabidopsis
  • DIS3 protein, Arabidopsis
  • Wiskott-Aldrich Syndrome Protein Family