One Active and Two Regulatory Sites

We extend the model of the previous section. Instead of one regulatory site we now have two sites, say R and / 2, which are identical and bind the effector R (Fig. 8.9). We still have one active site A, hence in the absence of the effector the binding isotherm 0 (Q, Cg = 0) is a simple Langmuir curve. 

The canonical PFs, Q, are expressed in terms of the molecular quantities in the usual manner. For instance, Q A, R, 0) is given by 

The intrinsic binding constants and the correlation functions are defined by 

we have three different correlations. In terms of these correlations the BI of A is 

Since the two regulatory sites are identical must be larger than unity (see Section 

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