Exploring the Theoretical Propensity for Liquid-Liquid Phase Separation in the Organization of Golgi Matrix Proteins

Abstract

AbstractThe Golgi apparatus, an essential cellular organelle, is fundamental in protein sorting and lipid metabolism. Comprising stacked, flattened sack-like structures, or cisternae, the Golgi displays distinct polarity with cis- and trans-faces that orchestrate different protein maturation and transport stages. Crucial to the Golgi integrity and organisation are the Golgi Matrix Proteins (GMPs), predominantly composed of Golgins and GRASPs. These proteins contribute to the Golgi’s distinctive stacked, polarised structure and ensure the appropriate localisation of resident Golgi enzymes, which are key for accurate protein processing. Even though the Golgi apparatus was unveiled over a century ago, the detailed mechanisms that control its structure remain elusive. Here, we highlight the significant prevalence of intrinsically disordered regions within GMPs across Eukarya. Intriguingly, these regions are linked to a high propensity for those proteins to form liquid-like condensates via Liquid-Liquid Phase Separation (LLPS). Biomolecular condensates are crucial in organising intracellular components into membrane-less organelles, such as Lewy bodies, the Corneal lens, and the nucleolus. Our findings pave the way for future investigations into the roles of disorder and LLPS in GMPs. Moreover, they provide a framework for understanding how these proteins might shape the architecture of the Golgi apparatus and the regulatory implications of phase separation in these processes.