RME-8, a conserved J-domain protein, is required for endocytosis in Caenorhabditis elegans
1Department of Biochemistry and Molecular Biophysics, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA.
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.
Related Concept Videos
Conservation of Protein Domains Over Different Proteins
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to form...
The Early Endosome: Endocytosis of Transferrin
Rab Proteins
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Directing Proteins to the Rough Endoplasmic Reticulum
Export of Misfolded Proteins out of the ER
Rab Cascades


