Rabaptin-5 is a direct effector of the small GTPase Rab5 in endocytic membrane fusion.
We have identified a novel 100 kDa coiled-coil protein, rabaptin-5, that specifically interacts with the GTP form of the small GTPase Rab5, a potent regulator of endocytic transport. It is mainly cytosolic, but a fraction colocalizes with Rab5 to early endosomes. Expression of a GTPase-deficient Rab5 mutant enhances the binding ... of rabaptin-5 to enlarged endosomes. Overexpression of rabaptin-5 alone is sufficient to promote expansion of early endosomes. Rab5 recruits rabaptin-5 to purified early endosomes in a GTP-dependent manner, demonstrating functional similarities with other members of the Ras superfamily. Immunodepletion of rabaptin-5 from cytosol strongly inhibits Rab5-dependent early endosome fusion. Rabaptin-5 is thus a Rab effector required for membrane docking and fusion.
Mesh Terms:
Amino Acid Sequence, Base Sequence, Cell-Free System, Cytosol, DNA, Complementary, Endocytosis, Endosomes, Fungal Proteins, GTP Phosphohydrolases, GTP-Binding Proteins, Gene Expression, Gene Library, Genetic Testing, Intracellular Membranes, Membrane Fusion, Membrane Proteins, Molecular Sequence Data, Protein Binding, Protein Structure, Secondary, Vesicular Transport Proteins, Yeasts, rab5 GTP-Binding Proteins
Amino Acid Sequence, Base Sequence, Cell-Free System, Cytosol, DNA, Complementary, Endocytosis, Endosomes, Fungal Proteins, GTP Phosphohydrolases, GTP-Binding Proteins, Gene Expression, Gene Library, Genetic Testing, Intracellular Membranes, Membrane Fusion, Membrane Proteins, Molecular Sequence Data, Protein Binding, Protein Structure, Secondary, Vesicular Transport Proteins, Yeasts, rab5 GTP-Binding Proteins
Cell
Date: Nov. 03, 1995
PubMed ID: 8521472
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