Before revision: A recent formulation of random-phase-approximation polymer theory for disordered protein phase separation is applied to investigate how the tendency for multiple chains of a protein to phase separate, as characterized by the critical temperature T^*_{\rm cr}, is related to the protein's single-chain average radius of gyration \langle R _g \rangle.
After revision: Liquid-liquid phase separation of intrinsically disordered proteins (IDPs) is a major undergirding factor in the regulated formation of URLanelles in the cell. The phase behavior of an IDP is sensitive to its amino acid sequence. Here we apply a recent random-phase-approximation polymer theory for disordered protein phase separation is applied to investigate how the tendency for multiple chains of a protein to phase separate, as characterized by the critical temperature T^*_{\rm cr}, is related to the protein's single-chain average radius of gyration \langle R _g \rangle.