Before revision:  Here, we propose a theory that explains the energetic " payout " of multivalency in the formalism of statistical mechanics. The model quantifies the dependence of binding entropy in a multivalent system on the geometry and flexibility of the binding partners .
After revision:  Here, we propose a theory that explains the energetic " payout " by a rigid tether. Meanwhile, evidence suggests that the tethers are largely disordered and offer little rigidity. Here we consider a mechanism to "prepay" the entropic costs of orienting the domains for binding, not through rigidity of the tether but through the careful spacing of the modifications on chromatin .