Hrs and hbp: possible regulators of endocytosis and exocytosis.
The molecular mechanisms of endocytosis and exocytosis are not yet fully understood. Hrs and Hbp, two tightly associated proteins in eukaryotic cells, have been implicated in these cellular processes. Hrs is homologous to Vps27p, an endosomal protein required for vacuolar and endocytic trafficking in yeast. Hrs is localized to early endosomes and is required for the normal morphology of early endosomes in mammalian cells. Hrs also associates with proteins implicated in endocytosis and exocytosis such as SNAP-25 and Eps15. Hrs treatment inhibits neurotransmitter release in permeabilized neuronal cells and its overexpression inhibits internalization of transferrin. Overexpression of dominant-negative Hbp mutants inhibits ligand-induced downregulation of growth factor/receptor complexes and immunoglobulin E receptor-triggered degranulation of secretory granules in mast cells. These observations suggest an important role for the Hrs/Hbp protein complex in vesicular trafficking during endocytosis and exocytosis.
Komada
M
M
Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan.
Kitamura
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N
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000502:physiology*; D004705:Endocytosis; D056827:Endosomal Sorting Complexes Required for Transport; D005089:Exocytosis; D005544:Forecasting; D051379:Mice; D010750:Phosphoproteins / Q000737:chemistry / Q000502:physiology*; D017434:Protein Structure, Tertiary; D021381:Protein Transport
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D010750:Phosphoproteins; C491648:Stam protein, mouse; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate