Myo6 facilitates the translocation of endocytic vesicles from cell peripheries.
Immunolocalization studies in epithelial cells revealed myo6 was associated with peripherally located vesicles that contained the transferrin receptor. Pulse-chase experiments after transferrin uptake showed that these vesicles were newly uncoated endocytic vesicles and that myo6 was recruited to these vesicles immediately after uncoating. GIPC, a putative myo6 tail binding protein, was also present. Myo6 was not present on early endosomes, suggesting that myo6 has a transient association with endocytic vesicles and is released upon early endosome fusion. Green fluorescent protein (GFP) fused to myo6 as well as the cargo-binding tail (M6tail) alone targeted to the nascent endocytic vesicles. Overexpression of GFP-M6tail had no effect on a variety of organelle markers; however, GFP-M6tail displaced the endogenous myo6 from nascent vesicles and resulted in a significant delay in transferrin uptake. Pulse-chase experiments revealed that transferrin accumulated in uncoated vesicles within the peripheries of transfected cells and that Rab5 was recruited to the surface of these vesicles. Given sufficient time, the transferrin did traffic to the perinuclear sorting endosome. These data suggest that myo6 is an accessory protein required for the efficient transportation of nascent endocytic vesicles from the actin-rich peripheries of epithelial cells, allowing for timely fusion of endocytic vesicles with the early endosome.
Aschenbrenner
Laura
L
Section of Cell and Developmental Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093, USA.
Lee
TinThu
T
Hasson
Tama
T
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000502:physiology; D051379:Mice; D008856:Microscopy, Fluorescence; D018995:Myosin Heavy Chains / Q000378:metabolism* / Q000502:physiology; D041681:NIH 3T3 Cells; D009479:Neuropeptides / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D011990:Receptors, Transferrin / Q000378:metabolism / Q000502:physiology; D022161:Transport Vesicles / Q000378:metabolism* / Q000502:physiology; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C492009:GIPC1 protein, human; C115271:Gipc1 protein, mouse; D008164:Luminescent Proteins; D009479:Neuropeptides; D011990:Receptors, Transferrin; C089785:myosin VI; D049452:Green Fluorescent Proteins; D018995:Myosin Heavy Chains; D020696:rab5 GTP-Binding Proteins