TY - JOUR T1 - cTAGE5 acts as a Sar1 GTPase regulator for collagen export JF - bioRxiv DO - 10.1101/452904 SP - 452904 AU - Norito Sasaki AU - Masano Shiraiwa AU - Miharu Maeda AU - Tomohiro Yorimitsu AU - Ken Sato AU - Toshiaki Katada AU - Kota Saito Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/10/25/452904.abstract N2 - Secretory proteins synthesized within the endoplasmic reticulum (ER) are exported via coat protein complex II (COPII)-coated vesicles. The formation of the COPII-coated vesicles is initiated by activation of the small GTPase, Sar1. cTAGE5 directly interacts with a guanine-nucleotide exchange factor (GEF), Sec12, and a GTPase-activating protein (GAP) of Sar1, Sec23. We have previously shown that cTAGE5 recruits Sec12 to the ER exit sites for efficient production of activated Sar1 for collagen secretion. However, the functional significance of the interaction between cTAGE5 and Sec23 has not been fully elucidated. In this study, we showed that cTAGE5 enhances the GAP activity of Sec23 toward Sar1. In addition, the interaction of cTAGE5 with Sec23 is necessary for collagen exit from the ER. Our data suggests that cTAGE5 acts as a Sar1 GTPase regulator for collagen secretion. ER -