Open AccessMicroscopic analysis of reconstituted COPII coat polymerization and Sec16 dynamics
Author(s) -
Iwasaki Hirohiko,
Tomohiro Yorimitsu,
Ken Sato
Publication year - 2017
Publication title -
journal of cell science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.384
H-Index - 278
eISSN - 1477-9137
pISSN - 0021-9533
DOI - 10.1242/jcs.203844
Subject(s) - copii , copi , endoplasmic reticulum , biology , microbiology and biotechnology , vesicular transport proteins , gtpase , secretory pathway , golgi apparatus , vacuolar protein sorting , endosome , intracellular
COPII coat and the small GTPase Sar1 mediate protein export from the endoplasmic reticulum (ER) via specialized domains known as the ER exit sites. The peripheral ER protein Sec16 has been proposed to organize ER exit sites. However, it remains unclear how these molecules drive COPII coat polymerization. Here, we characterized the spatiotemporal relationships between the COPII components during their polymerization using fluorescence microscopy combined with an artificial planar membrane. We demonstrated that Sar1 dissociates from the membrane shortly after the COPII coat recruitment, and Sar1 is then no longer required for the COPII coat to bind to the membrane. Furthermore, we found that Sec16 is incorporated within the COPII-cargo clusters, which is dependent on the Sar1 GTPase cycle. These data show how Sar1 drives the polymerization of COPII coat and how Sec16 is spatially distributed during COPII coat polymerization.