Muscarinic toxin 1

Origin

Muscarinic toxin 1 was originally isolated from mamba venom and consists of 65 to 66 amino acid residues with four intramolecular disulfide bonds. Recent studies have shown that activation of muscarinic acetylcholine receptors regulates the metabolism of β-amyloid precursor proteins, and that muscarinic agonists reduce the production of amyloid-β proteins.

Biological Functions

Muscarinic toxin 1 has non-competitive interactions with adrenergic and muscarinic receptors. Binds to alpha-2b (ADRA2B) (IC50=2.3 nM), alpha-1a (ADRA1A), alpha-1b (ADRA1B) and alpha-2c (ADRA2C) adrenergic receptors. Reversibly binds to the M1 (CHRM1) muscarinic acetylcholine receptor, probably through interaction with the orthosteric site. Also has slightly weaker effects on M3 (CHRM3) and M4 (CHRM4) receptors. The order of potency is ADRA2B>>CHRM1>ADRA1A>ADRA1B>ADRA2C/CHRM4 (PubMed:24793485).