title: Two potent central convulsant peptides, a bee venom toxin, the MCD peptide, and a snake venom toxin, dendrotoxin I, known to block K+ channels, have interacting receptor sites.
abstract: Both the bee venom toxin, mast cell degranulating peptide (MCD peptide) and the mamba toxin dendrotoxin I are potent central convulsants. The two specific receptor sites for these two types of polypeptide toxins are in allosteric interaction in brain membranes. Occupation of the dendrotoxin I binding site (KI = 0.4 nM) prevents binding of the 125I-MCD peptide to its own receptor (KI = 0.23 nM). This inhibition is of the non-competitive type. Autoradiography has shown that a high enough dendrotoxin I concentration (30 nM) prevented binding of 125I MCD peptide to all brain structures where specific receptors had been identified. A lower concentration of the mamba toxin led to a nearly selective inhibition of MCD peptide binding to the hippocampal region which is responsible for the convulsant properties of the 2 types of polypeptide toxins.
mesh_terms: D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D000818:Animals; D001514:Bee Venoms / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D003292:Convulsants; D004546:Elapid Venoms / Q000378:metabolism* / Q000494:pharmacology; D006131:Growth Inhibitors; D015850:Interleukin-6; D007425:Intracellular Membranes / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000302:isolation & purification* / Q000502:physiology; D009498:Neurotoxins / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism* / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels; D051381:Rats; D011950:Receptors, Cholinergic / Q000378:metabolism*; D018000:Receptors, Peptide; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D001514:Bee Venoms; D003292:Convulsants; D004546:Elapid Venoms; D006131:Growth Inhibitors; D015850:Interleukin-6; D007473:Ion Channels; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines; D009498:Neurotoxins; D010455:Peptides; D015221:Potassium Channels; D011950:Receptors, Cholinergic; D018000:Receptors, Peptide; C042467:dendrotoxin receptor; C051855:mast cell degranulating peptide receptor; C008331:mast cell degranulating peptide; C020273:dendrotoxin; D011188:Potassium