RNA scaffolds the Golgi ribbon by forming condensates with GM130.

The mammalian Golgi is composed of stacks that are laterally connected into a continuous ribbon-like structure. The integrity and function of the ribbon is disrupted under stress conditions, but the molecular mechanisms remain unclear. Here we show that the ribbon is maintained by biomolecular condensates of RNA and the Golgi matrix protein GM130 (GOLGA2). We identify GM130 as a membrane-bound RNA-binding protein, which directly recruits RNA and associated RNA-binding proteins to the Golgi membrane. Acute degradation of RNA or GM130 in cells disrupts the ribbon. Under stress conditions, RNA dissociates from GM130 and the ribbon is disjointed, but after the cells recover from stress the ribbon is restored. When overexpressed in cells, GM130 forms RNA-dependent liquid-like condensates. GM130 contains an intrinsically disordered domain at its amino terminus, which binds RNA to induce liquid-liquid phase separation. These co-condensates are sufficient to link purified Golgi membranes, reconstructing lateral linking of stacks into a ribbon-like structure. Together, these studies show that RNA acts as a structural biopolymer that together with GM130 maintains the integrity of the Golgi ribbon.

Zhang Y ，Seemann J 《-》

The biogenesis of the Golgi ribbon: the roles of membrane input from the ER and of GM130.

Marra P ，Salvatore L ，Mironov A Jr ，Di Campli A ，Di Tullio G ，Trucco A ，Beznoussenko G ，Mironov A ，De Matteis MA ... -  《MOLECULAR BIOLOGY OF THE CELL》

Liquid-liquid phase separation of the Golgi matrix protein GM130.

Golgins are an abundant class of peripheral membrane proteins of the Golgi. These very long (50-400 nm) rod-like proteins initially capture cognate transport vesicles, thus enabling subsequent SNARE-mediated membrane fusion. Here, we explore the hypothesis that in addition to serving as vesicle tethers, Golgins may also possess the capacity to phase separate and, thereby, contribute to the internal organization of the Golgi. GM130 is the most abundant Golgin at the cis Golgi. Remarkably, overexpressed GM130 forms liquid droplets in cells analogous to those described for numerous intrinsically disordered proteins with low complexity sequences, even though GM130 is neither low in complexity nor intrinsically disordered. Virtually pure recombinant GM130 also phase-separates into dynamic, liquid-like droplets in close to physiological buffers and at concentrations similar to its estimated local concentration at the cis Golgi.

Rebane AA ，Ziltener P ，LaMonica LC ，Bauer AH ，Zheng H ，López-Montero I ，Pincet F ，Rothman JE ，Ernst AM ... -  《-》

GM130 and GRASP65-dependent lateral cisternal fusion allows uniform Golgi-enzyme distribution.

Puthenveedu MA ，Bachert C ，Puri S ，Lanni F ，Linstedt AD ... -  《NATURE CELL BIOLOGY》

Structural basis for the interaction between the Golgi reassembly-stacking protein GRASP65 and the Golgi matrix protein GM130.

GM130 and GRASP65 are Golgi peripheral membrane proteins that play a key role in Golgi stacking and vesicle tethering. However, the molecular details of their interaction and their structural role as a functional unit remain unclear. Here, we present the crystal structure of the PDZ domains of GRASP65 in complex with the GM130 C-terminal peptide at 1.96-Å resolution. In contrast to previous findings proposing that GM130 interacts with GRASP65 at the PDZ2 domain only, our crystal structure of the complex indicates that GM130 binds to GRASP65 at two distinct sites concurrently and that both the PDZ1 and PDZ2 domains of GRASP65 participate in this molecular interaction. Mutagenesis experiments support these structural observations and demonstrate that they are required for GRASP65-GM130 association.

Hu F ，Shi X ，Li B ，Huang X ，Morelli X ，Shi N ... -  《-》