title: Association of Endophilin B1 with Cytoplasmic Vesicles.
abstract: Endophilins are SH3- and BAR domain-containing proteins implicated in membrane remodeling and vesicle formation. Endophilins A1 and A2 promote the budding of endocytic vesicles from the plasma membrane, whereas endophilin B1 has been implicated in vesicle budding from intracellular organelles, including the trans-Golgi network and late endosomes. We previously reported that endophilins A1 and A2 exist almost exclusively as soluble dimers in the cytosol. Here, we present results of fluorescence fluctuation spectroscopy analyses indicating that, in contrast, the majority of endophilin B1 is present in multiple copies on small, highly mobile cytoplasmic vesicles. Formation of these vesicles was enhanced by overexpression of wild-type dynamin 2, but suppressed by expression of a catalytically inactive dynamin 2 mutant. Using dual-color heterospecies partition analysis, we identified the epidermal growth factor receptor on endophilin B1 vesicles. Moreover, a proportion of endophilin B1 vesicles also contained caveolin, whereas clathrin was almost undetectable on those vesicles. These results raise the possibility that endophilin B1 participates in dynamin 2-dependent formation of a population of transport vesicles distinct from those generated by A-type endophilins.
authors: Department of Physics, University of Minnesota, Minneapolis, Minnesota.
authors: Jinhui
authors: J
authors: Li
authors: UT Southwestern Medical Center, Dallas, Texas.
authors: Barbara
authors: B
authors: Barylko
authors: Department of Physics, University of Minnesota, Minneapolis, Minnesota.
authors: John P
authors: JP
authors: Eichorst
authors: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota.
authors: Joachim D
authors: JD
authors: Mueller
authors: UT Southwestern Medical Center, Dallas, Texas.
authors: Joseph P
authors: JP
authors: Albanesi
authors: Department of Physics, University of Minnesota, Minneapolis, Minnesota. Electronic address: chen@physics.umn.edu.
authors: Yan
authors: Y
authors: Chen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D022461:Caveolins / Q000378:metabolism; D002460:Cell Line; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D034286:Dynamin III / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D008024:Ligands; D011485:Protein Binding; D021381:Protein Transport; D051381:Rats
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D022461:Caveolins; D008024:Ligands; C429293:SH3GLB1 protein, human; C512478:EGFR protein, human; D066246:ErbB Receptors; D034286:Dynamin III