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

Abstract

Eukaryotic cells evolved to possess efficient secretory machinery capable of transporting a significant fraction of their proteome. The number of proteins predicted to enter the secretory pathway can reach up to 36% of the total proteome in humans (1). Proteins entering the secretory pathway are efficiently sorted to a specific destination: the extracellular space, the plasma membrane, or the interior of the endomembrane system. The machinery also has efficient quality control, avoiding the transport of misfolded proteins or complexes (2). Proteins destined for this classical secretory pathway are synthesised in the endoplasmic reticulum (ER) interior, where they are first folded and possibly modified by the post-translation ER machinery (2). Subsequently, these secretory cargoes are transferred to the ER exit sites (ERES), where they are assembled into secretory vesicles coated with coatomers (COPII), routered for the ER-Golgi intermediate compartment (ERGIC), and later to the cis-Golgi face (3, 4).