RRC ID 29007
Author Rivero F, Albrecht R, Dislich H, Bracco E, Graciotti L, Bozzaro S, Noegel AA.
Title RacF1, a novel member of the Rho protein family in Dictyostelium discoideum, associates transiently with cell contact areas, macropinosomes, and phagosomes.
Journal Mol Biol Cell
Abstract Using a PCR approach we have isolated racF1, a novel member of the Rho family in Dictyostelium. The racF1 gene encodes a protein of 193 amino acids and is constitutively expressed throughout the Dictyostelium life cycle. Highest identity (94%) was found to a RacF2 isoform, to Dictyostelium Rac1A, Rac1B, and Rac1C (70%), and to Rac proteins of animal species (64-69%). To investigate the role of RacF1 in cytoskeleton-dependent processes, we have fused it at its amino-terminus with green fluorescent protein (GFP) and studied the dynamics of subcellular redistribution using a confocal laser scanning microscope and a double-view microscope system. GFP-RacF1 was homogeneously distributed in the cytosol and accumulated at the plasma membrane, especially at regions of transient intercellular contacts. GFP-RacF1 also localized transiently to macropinosomes and phagocytic cups and was gradually released within <1 min after formation of the endocytic vesicle or the phagosome, respectively. On stimulation with cAMP, no enrichment of GFP-RacF1 was observed in leading fronts, from which it was found to be initially excluded. Cell lines were obtained using homologous recombination that expressed a truncated racF1 gene lacking sequences encoding the carboxyl-terminal region responsible for membrane targeting. These cells displayed normal phagocytosis, endocytosis, and exocytosis rates. Our results suggest that RacF1 associates with dynamic structures that are formed during pinocytosis and phagocytosis. Although RacF1 appears not to be essential, it might act in concert and/or share functions with other members of the Rho family in the regulation of a subset of cytoskeletal rearrangements that are required for these processes.
Volume 10(4)
Pages 1205-19
Published 1999-4-1
DOI 10.1091/mbc.10.4.1205
PMID 10198067
PMC PMC25253
MeSH Amino Acid Sequence Animals Base Sequence Carrier Proteins / chemistry Carrier Proteins / genetics Carrier Proteins / metabolism* Cloning, Molecular Dictyostelium / genetics Dictyostelium / physiology* Exocytosis GTP-Binding Proteins / chemistry GTP-Binding Proteins / genetics GTP-Binding Proteins / metabolism* Intercellular Junctions / physiology* Molecular Sequence Data Organelles / physiology* Phagosomes / physiology* Phylogeny Pinocytosis Polymerase Chain Reaction Recombinant Fusion Proteins / chemistry Recombinant Fusion Proteins / metabolism Sequence Alignment Sequence Homology, Amino Acid rac GTP-Binding Proteins
IF 3.791
Times Cited 51
Cellular slime molds S00248 S00292