Cloning and characterization of a novel actin binding protein in Drosophila melanogaster. N.W. O'Brien. Molecular Biology Institute, San Diego State University, San Diego, CA.

   Regulation of the actin cytoskeletal network is important for many cellular processes including cell shape, intercellular adhesion, cell migration and development. During development, most cells are pluripotent and receive cues from their environment to allow them to adopt specific cell fates. Many of these cell fates involve cell shape changes or the migration of groups of cells in a specific spatiotemporal fashion to allow the proper structure and positioning of these cells relative to other tissues. It is conceivable that specific actin binding proteins might be mediators of regulating the actin cytoskeletal network changes, which can lead to proper cell fate determination, structure or function.
   We are thus characterizing a novel putative actin binding protein in Drosophila. dabp contains a 1.9 kb transcript encoding a protein of 592 amino acid residues, and is cytologically located at 89E3. Based on homology, this protein is predicted to contain a coiled coil domain, a calponin homology (CH) domain, along with several putative phosphorylation sites and is thus a candidate protein to be involved in the regulation of cellular events which might lead to changes in cell shape, motility or adhesion. This gene represents a novel member of a new family of actin binding proteins having a CH domain at its C terminal rather than N terminal end. A second member of this family has been identified on the X chromosome. Northern analysis indicates that dabp is expressed at similar levels throughout development and currently, we are doing in situ hybridization in order to determine specific tissues expressing this gene. RNA interference studies combined with an enhancer trap mutagenesis scheme will also be employed to look at the specific effects of dabp disruption on the cytoskeleton and in proper development, providing us insight into the role of dabp during these processes. (Supported by the MDA.).