Organelle morphogenesis by active membrane remodeling

Intracellular organelles are subject to a steady flux of lipids and proteins through active{,} energy consuming transport processes. Active fission and fusion are promoted by GTPases{,} e.g.{,} Arf-Coatamer and the Rab-Snare complexes{,} which both sense and generate local membrane curvature. Here we investigate{,} through Dynamical Triangulation Monte Carlo simulations{,} the role that these active processes play in determining the morphology and composition segregation in closed membranes. We find that the steady state shapes obtained as a result of such active processes{,} bear a striking resemblance to the ramified morphologies of organelles in vivo{,} pointing to the relevance of nonequilibrium fission-fusion in organelle morphogenesis.