Reproducing the dynamics of proteins and/or nucleic acids in a solution in which microdroplets of the similar size as cells or organelles are emerged by liquid-liquid phase separation, is an excellent model system. This is a powerful and rewarding strategy for understanding the properties of living cells. The targets of that research also include the formation of membraneless organelles, which has been gaining more attention in recent years. Here, the current results of our research using representative biopolymers, actin cytoskeleton and DNA, and phospholipids that are important components of biological membranes, would be introduced.
Liquid-liquid phase separation (LLPS) is recognized as a mechanism for regulation of enzymatic activity. Biochemical mechanisms include concentrating reactants to enhance reaction rates or sequester enzymes and reactants from each other to reduce the reaction rate. On the other hand, LLPS might also regulate the diffusion of small molecules or important parameters for enzymatic activity (such as modulators, macromolecular crowding and changing the media physicochemical features) increasing or decreasing the reaction rate of the enzymes. Furthermore, the co-compartmentalization of specific enzymes can favour or speed up specific metabolic fluxes. Here, we discuss how LLPS contributed to generate a new era for enzyme regulation and the new possible subtle regulation mechanisms still unexplored.
Prostaglandins (PGs), lipid mediators, exert various effects in vivo through receptor-mediated signal transduction, and the elucidation of the molecular mechanisms of signal transduction by structural biology of PG receptors is expected to contribute to drug discovery. We have elucidated the molecular mechanisms of ligand binding mode, signal transduction mechanism, and G protein selectivity through structural analysis of PG receptors. In this paper, we would like to introduce the structure and function of GPCRs revealed through structural biology of PG receptors.