title: RME-8, a conserved J-domain protein, is required for endocytosis in Caenorhabditis elegans.
abstract: By genetic analysis of Caenorhabditis elegans mutants defective in yolk uptake, we have identified new molecules functioning in the endocytosis pathway. Here we describe a novel J-domain-containing protein, RME-8, identified by such genetic analysis. RME-8 is required for receptor-mediated endocytosis and fluid-phase endocytosis in various cell types and is essential for C. elegans development and viability. In the macrophage-like coelomocytes, RME-8 localizes to the limiting membrane of large endosomes. Endocytosis markers taken up by the coelomocytes rapidly accumulate in these large RME-8-positive endosomes, concentrate in internal subendosomal structures, and later appear in RME-8-negative lysosomes. rme-8 mutant coelomocytes fail to accumulate visible quantities of endocytosis markers. These observations show that RME-8 functions in endosomal trafficking before the lysosome. RME-8 homologues are found in multicellular organisms from plants to humans but not in the yeast Saccharomyces cerevisiae. These sequence homologies suggest that RME-8 fulfills a conserved function in multicellular organisms.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: B
authors.initials: B
authors.lastname: Grant
authors.forename: D
authors.initials: D
authors.lastname: Hirsh
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D002455:Cell Division; D017124:Conserved Sequence; D018509:DNA, Helminth; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism; D015870:Gene Expression; D017238:Genes, Helminth / Q000502:physiology; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
chemical_list: D029742:Caenorhabditis elegans Proteins; D018509:DNA, Helminth; D015801:Helminth Proteins; D018832:Molecular Chaperones; C439316:RME-8 protein, C elegans