title: Early changes in the distribution and organization of microfilament proteins during cell transformation.
abstract: During the onset of transformation, Rous sarcoma virus-infected cells undergo characteristic morphological changes that reflect the biochemical events induced by the viral src gene. Temperature downshift experiments using chick embryo cells infected with transformation-defective temperature-sensitive viral mutants have shown two major morphological changes occurring at different times in the transformation process: ruffle-like flowers appear on the dorsal cell surface as early as 15 min after temperature shift, while later, between 6 and 12 hr, cytoskeletal stress fibers disappear and the cells round up. We report that flowers contain large accumulations of the cytoskeletal proteins actin, alpha-actinin, myosin and tropomyosin. Furthermore, since flowers stain very intensely with fluorescein-labeled phalloidin, a cyclopeptide that selectively binds to F-actin and not to G-actin, we suggest that these structures result from an early reorganization of microfilaments.
mesh_terms: D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D002642:Chick Embryo; D003599:Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D005814:Genes, Viral; D007700:Kinetics; D008163:Luminescent Measurements; D008854:Microscopy, Electron; D014764:Viral Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D014764:Viral Proteins