Unexpected Control of Protein Self-Association by Translation Initiation

Living proteomes are necessarily far from equilibrium. It is paradoxical, then, that reducing protein influx -- which should promote equilibration -- instead, prolongs life. We therefore reasoned that kinetic barriers to equilibration must exist and that these decrease with protein influx. We further hypothesized that the probabilistic nucleation of ordered protein assemblies such as amyloids could underlie those barriers. To investigate the effects of influx on protein self-assembly, we used our quantitative reporter of nucleation-limited protein self-assembly (termed Distributed Amphifluoric FRET or DAmFRET) to probe kinetic barriers to self-assembly of structurally diverse protein assemblies at different rates of translation initiation in living cells.