MAOIs: Multiple Effects and Sites of Action

Beth Levant
blevant@kumc.edu

Hi Rita-

The Bmax for 3H-quin is about half that of 3H-spip and that's about what you'd expect based on the assumption that 3H-quin, being an agonist, is labeling only the D2-like sites in the high affinity conformation and about half the D2-like sites are in the high affinity state (at least according to the literature).  So, I'm still trying to figure out the dichotomy between 3H-quin doing everything a D2 agonist should do and the interaction with MAOIs.

On thing that I think is really interesting with your work, if I'm understanding it correctly, is that many of the compounds that interact with the I2 site on MAO, also inhibit MAO via actions at the catalytic site.  Based on our data, it's unlikely that the I2 site is involved in the 3H-quin interaction, but the model of multiple binding sites on one protein might be applied to our question as well.