title: The J-domain protein Rme-8 interacts with Hsc70 to control clathrin-dependent endocytosis in Drosophila.
abstract: By screening for mutants exhibiting interactions with a dominant-negative dynamin, we have identified the Drosophila homologue of receptor-mediated endocytosis (Rme) 8, a J-domain-containing protein previously shown to be required for endocytosis in Caenorhabditis elegans. Analysis of Drosophila Rme-8 mutants showed that internalization of Bride of sevenless and the uptake of tracers were blocked. In addition, endosomal organization and the distribution of clathrin were greatly disrupted in Rme-8 cells, suggesting that Rme-8 participates in a clathrin-dependent process. The phenotypes of Rme-8 mutants bear a strong resemblance to those of Hsc70-4, suggesting that these two genes act in a common pathway. Indeed, biochemical and genetic data demonstrated that Rme-8 interacts specifically with Hsc70-4 via its J-domain. Thus, Rme-8 appears to function as an unexpected but critical cochaperone with Hsc70 in endocytosis. Because Hsc70 is known to act in clathrin uncoating along with auxilin, another J-protein, its interaction with Rme-8 indicates that Hsc70 can act with multiple cofactors, possibly explaining its pleiotropic effects on the endocytic pathway.
authors.affiliation: Dept. of Cell Biology, Ludwig Institute for Cancer Research, Yale University School of Medicine, 333 Cedar Street, PO Box 208002, New Haven, CT 06520-8002, USA.
authors.forename: Henry C
authors.initials: HC
authors.lastname: Chang
authors.forename: Michael
authors.initials: M
authors.lastname: Hull
authors.forename: Ira
authors.initials: I
authors.lastname: Mellman
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000378:metabolism*; D002966:Clathrin / Q000502:physiology*; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D017931:DNA Primers; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D004705:Endocytosis / Q000502:physiology*; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D018832:Molecular Chaperones; D016296:Mutagenesis; D016133:Polymerase Chain Reaction; D012160:Retina / Q000502:physiology / Q000648:ultrastructure; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D029742:Caenorhabditis elegans Proteins; D002966:Clathrin; D017931:DNA Primers; D029721:Drosophila Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; C439316:RME-8 protein, C elegans; C489292:Rme-8 protein, Drosophila