ER-to-Golgi transport visualized in living cells.
Newly synthesized proteins that leave the endoplasmic reticulum (ER) are funnelled through the Golgi complex before being sorted for transport to their different final destinations. Traditional approaches have elucidated the biochemical requirements for such transport and have established a role for transport intermediates. New techniques for tagging proteins fluorescently have made it possible to follow the complete life history of single transport intermediates in living cells, including their formation, path and velocity en route to the Golgi complex. We have now visualized ER-to-Golgi transport using the viral glycoprotein ts045 VSVG tagged with green fluorescent protein (VSVG-GFP). Upon export from the ER, VSVG-GFP became concentrated in many differently shaped, rapidly forming pre-Golgi structures, which translocated inwards towards the Golgi complex along microtubules by using the microtubule minus-end-directed motor complex of dynein/dynactin. No loss of fluorescent material from pre-Golgi structures occurred during their translocation to the Golgi complex and they frequently stretched into tubular shapes. Together, our results indicate that these pre-Golgi carrier structures moving unidirectionally along microtubule tracks are responsible for transporting VSVG-GFP through the cytoplasm to the Golgi complex. This contrasts with the traditional focus on small vesicles as the primary vehicles for ER-to-Golgi transport.
Presley
J F
JF
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, NIH, Bethesda, Maryland 20892, USA.
Cole
N B
NB
Schroer
T A
TA
Hirschberg
K
K
Zaal
K J
KJ
Lippincott-Schwartz
J
J
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D019556:COS Cells; D000072159:Dynactin Complex; D004398:Dyneins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005453:Fluorescence; D006056:Golgi Apparatus / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D007091:Image Processing, Computer-Assisted; D007425:Intracellular Membranes / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism
D000072159:Dynactin Complex; C028391:G protein, vesicular stomatitis virus; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D008869:Microtubule-Associated Proteins; D011993:Recombinant Fusion Proteins; D014759:Viral Envelope Proteins; D049452:Green Fluorescent Proteins; D004398:Dyneins; D015739:Nocodazole