RT Journal Article
SR Electronic
T1 COPII-coated membranes function as transport carriers of intracellular procollagen-1
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 110700
DO 10.1101/110700
A1 Amita Gorur
A1 Lin Yuan
A1 Samuel J Kenny
A1 Satoshi Baba
A1 Ke Xu
A1 Randy Schekman
YR 2017
UL http://biorxiv.org/content/early/2017/02/21/110700.abstract
AB The coat protein complex II (COPII) is essential for the secretion of large cargo, such as the 300 nm precursor fibrils of procollagen I (PC1). Previous work has shown that the CUL3-KLHL12 complex increases the size of COPII vesicles to over 300 nm in diameter and accelerates the secretion of PC1; however, the role of large COPII vesicles as PC1 transport carriers was not unambiguously demonstrated. In this study, using stochastic optical reconstruction microscopy (STORM), correlated light electron microscopy (CLEM), and live cell imaging we report the existence of mobile COPII-coated vesicles that completely encapsulate the cargo PC1 and are physically separated from ER. We have also developed a cell-free COPII vesicle budding reaction that reconstitutes the capture of PC1 into large COPII vesicles. This process requires COPII proteins and the GTPase activity of the COPII subunit SAR1. We conclude from in vivo and in vitro evidence that large COPII vesicles are bona fide carriers of PC1.Summary COPII may play a direct or indirect role in the traffic of large protein complexes such as procollagen. Using high resolution imaging techniques in intact cells and in vitro reconstituted vesicles, Gorur et al. show that COPII coated vesicles carry procollagen1.BFAbrefeldin ACLEMCorrelative light electron microscopyCOPIICoat protein complex IIERESER exit sitesERGICER Golgi intermediate compartmentPCprocollagenPC1procollagen IPFAParaformaldehydeSTORMStochastic optical reconstruction microscopyRTRoom temperature