Targeted wild-type and jerker espins reveal a novel, WH2-domain-dependent way to make actin bundles in cells

Patricia A. Loomis, Alexander E. Kelly, Lili Zheng, Benjarat Changyaleket, Gabriella Sekerková, Enrico Mugnaini, Adriana Ferreira, R. Dyche Mullins, James R. Bartles*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The espin actin-bundling proteins, which are the target of deafness mutations, are present in the parallel actin bundles of stereocilia and microvilli and appear to increase their steady-state length. Here, we report a new activity of the espins, one that depends on their enigmatic WH2 domain: the ability to assemble a large actin bundle when targeted to a specific subcellular location. This activity was observed for wild-type espins targeted to the centrosome in transfected neuronal cells and for jerker espins targeted to the nucleolus in a wide variety of transfected cells as a result of the frameshifted peptide introduced into the espin C-terminus by the jerker deafness mutation. This activity, which appears specific to espins, requires two espin F-actin-binding sites and the actin-monomer-binding activity of the espin WH2 domain, but can be mimicked by adding a WH2 domain to an unrelated actin-bundling protein, villin. Espins do not activate the Arp2/3 complex in vitro, and bundle assembly is not indicative of in-vitro nucleation activity. Our results suggest a novel way to build actin bundles at specific sites in cells.

Original languageEnglish (US)
Pages (from-to)1655-1665
Number of pages11
JournalJournal of cell science
Issue number8
StatePublished - Apr 15 2006


  • Hearing
  • Microtubule
  • Neuron
  • Nucleus
  • RS domain
  • WASP

ASJC Scopus subject areas

  • Cell Biology


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