Villin-like actin-binding proteins are expressed ubiquitously in Arabidopsis

In an attempt to elucidate the biological function of villin-like actin-bin ding proteins in plants we have cloned several genes encoding Arabidopsis p roteins with high homology to animal villin. We found that Arabidopsis cont ains at least four villin-like genes (AtVLNs) encoding four different VLN i soforms. Two AtVLN isoforms are more closely related to mammalian villin in their primary structure and are also antigenically related, whereas the ot her two contain significant changes in the C-terminal headpiece domain. RNA and promoter/beta-glucuronidase expression studies demonstrated that AtVLN genes are expressed in all organs, with elevated expression levels in cert ain types of cells. These results suggest that AtVLNs have less-specialized functions than mammalian villin, which is found only in the microvilli of brush border cells, Immunoblot experiments using a monoclonal antibody agai nst pig villin showed that AtVLNs are widely distributed in a variety of pl ant tissues. Green fluorescent protein fused to full-length AtVLN and indiv idual AtVLN headpiece domains can bind to both animal and plant actin filam ents in vivo.