I was looking for, but couldn't find, any comprehensive information on what science knows about the pharmacology of harmala alkaloids. There is mention made of NMDA inverse agonism, possible GABA interaction, obviously MAOI activity...

Could anyone who's researched the topic give a brief overview of what receptors we know harmala alkaloids to interact with?

Has anyone found any evidence that they interact directly with 5-HT receptors like psilocin?

Here's what I found:
"Harmaline produces a tremor which is prevented by diazepam. [...] While harmaline has a low affinity for the receptor (IC50 approximately 600 μM), tremorogenic (i.p.) doses of harmaline produce brain concentrations sufficient to occupy some benzodiazepine binding sites."
http://www.sciencedirect.com/science/article/pii/0014299980900205

"Our hypothesis is that harmaline produces tremor by acting as an inverse agonist at the MK-801 binding site and thus opening the cation channel."
http://www.sciencedirect.com/science/article/pii/S0006899397006069

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I know binding site data isn't really useful for the experience of drinking harmal tea, but it really is fascinating to read about nonetheless.