Figure 5. A protein-protein interaction subgraph showing the proteasome subunits, where nodes denote proteins and the edges describe protein-protein interaction.

Two local hub proteins of this subgraph (Psma2 and Psma3) belong to cell line-specific proteins, while a candidate balancer protein (Psmb6) represents a connection between these two modules (see discussion for details). This supports our assumption that balancer proteins could be connective hubs between different modules. Protein marked in green: Psma2; yellow: Psmb6; magenta: Psma3.