A-D (a) In native protein structures, APRs (red) are usually buried within the hydrophobic core, rendering them harmless (structure adopted from PDB-entry 2AC0). Exposure of these APRs however (b), can lead to formation of highly stable aggregated species (c & d, structure adopted from PDB-entry 2M5N) that are detrimental to both protein function and cellular viability. Aggregation GKs (R, K, E and D, green) decrease APR-mediated aggregation tendency through charge repulsion. In doing so, GKs alleviate the threat posed by APRs and push the balance towards the native fold as indicated by the green arrows. 