ER to Golgi transport vesicle fused with cis-Golgi ER to Golgi transport vesicle GOLGA2 phosphorylated by CDK1 is unable to promote fusion of ER to Golgi transport vesicles with cis-Golgi Authored: Orlic-Milacic, M, 2012-07-20 Edited: Gillespie, ME, 2012-08-07 Pubmed10679020 Pubmed18167358 Pubmed9753325 Reactome Database ID Release 432314569 Reactome, http://www.reactome.org ReactomeREACT_147730 Reviewed: Colanzi, Antonino, 2012-08-21 Reviewed: Malhotra, Vivek, 2012-08-15 Reviewed: Wang, Yanzhuang, 2012-08-19 USO1 (p115) protein, localizing to membranes of ER to Golgi transport vesicles, binds GOLGA2 (GM130), localizing to membranes of cis-Golgi cisternae. Binding of USO1 to GOLGA2 enables tethering of ER to Golgi transport vesicles to cis-Golgi cisternae, and is facilitated by a Ras-related GTPase RAB1. Fusion of ER to Golgi transport vesicles with cis-Golgi succeeds tethering and depends on STX5 (syntaxin-5). In mitosis, phosphorylation of GOLGA2 by cyclin B-activated CDK1 prevents USO1 docking. This results in cessation of ER to Golgi transport. Halting ER to Golgi transport increases the number of transport vesicles at the expense of Golgi cisternae, since transport vesicles keep budding from the ER but are unable to fuse with Golgi cisternae and deliver their content (Lowe et al. 1998, Seeman et al. 2000, Diao et al. 2008).