title: Induction of ras gene expression by homologous aggregation factor in cells from the sponge Geodia cydonium.
abstract: Northern blot data as well as immunocytochemical and immunoblotting experiments indicate that the sponge Geodia cydonium contains the ras gene (or ras-related gene). The ras gene transcript has a size of 1.5 kilobases and the ras gene product has an Mr of 23,000-26,000. While dissociated G. cydonium cells lack ras gene product, ras gene expression can be induced by incubating the cells with the cell-binding fragment of the homologous aggregation factor. Maximal expression was observed 10-15 h after addition of the fragment. The sponge ras protein was partially purified by immunoprecipitation and bound GTP with a dissociation constant of 1.8 x 10(-6) M. It was found to be associated with the cell membrane. Autoradiographic studies revealed that the ras protein binds to the plasma membrane-associated anti-aggregation receptor and thereby mediates the mitogenic response, caused by the homologous lectin. It is hypothesized that sponges are provided in addition to the aggregation factor-caused and protein kinase C-mediated pathway with a second mechanism of transduction of mitotic signals, the lectin-caused and ras-mediated signaling.
authors: Institut für Physiologische Chemie, Abt. Angewandte Molekularbiologie, Mainz, West Germany.
authors: H C
authors: HC
authors: Schröder
authors: Y
authors: Y
authors: Kuchino
authors: M
authors: M
authors: Gramzow
authors: B
authors: B
authors: Kurelec
authors: U
authors: U
authors: Friese
authors: G
authors: G
authors: Uhlenbruck
authors: W E
authors: WE
authors: Müller
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D015815:Cell Adhesion Molecules; D011905:Genes, ras; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics; D009693:Nucleic Acid Hybridization; D011161:Porifera / Q000235:genetics*; D011506:Proteins / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D014158:Transcription, Genetic
chemical_list: D015815:Cell Adhesion Molecules; D008565:Membrane Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; C013065:cell aggregation factors; D012313:RNA; D006160:Guanosine Triphosphate; D016283:Proto-Oncogene Proteins p21(ras)