文摘
MT1, 2 (Adem et al., 1988) and 3 (Jolkkonen et al., 1994) (same as m4-toxin; Max et al., 1993) have been isolated from Dendroaspis angusticeps venom. From radioligand binding experiments with relatively selective antagonists, it was suggested that MT1 and 2 bound selectively to m1 central muscarinic receptor (Jerusalinsky et al., 1992). The Kis for MT1 and MT2, in synaptosomal membranes from cerebral cortex were range from 20-100 nM. In assays with cloned human muscarinic receptors, it was shown that both toxins have high affinity for m1 and slightly lower for m4 receptor. While MT1 and 2 have very little affinity for m5 and do not bind to m2 or m3, MT3 exhibited the highest affinity for m4 (Ki