Monoclonal antibodies can uncouple the main alpha-latrotoxin effects: toxin-induced Ca2+ influx and stimulated neurotransmitter release.
A panel of monoclonal antibodies has been produced against alpha-latrotoxin using black widow spider venom. Five of them were characterized relative to their affinity for alpha-latrotoxin and ability to modify the main toxin effects--to increase calcium permeability of synaptosomes, to stimulate the neurotransmitter release and to form the ion channels in artificial lipid membrane. The results reported here show that: (i) the monoclonal antibodies do not alter the alpha-latrotoxin affinity for the membrane acceptor; (ii) two monoclonal antibodies, A6 and A24, can simultaneously inhibit the alpha-latrotoxin induced Ca2+ uptake and GABA release; (iii) monoclonal antibodies A4 completely block the toxin-induced Ca2+ uptake, but decrease partially the rate of GABA release; (iv) monoclonal antibodies A15 that do not modify the alpha-latrotoxin ability to stimulate Ca2+ uptake and GABA release are able to alter the properties of channels formed by the toxin in the artificial lipid bilayer. From these data we hypothesize that the alpha-latrotoxin molecule has separate functional sites which provide a high-affinity binding to the membrane acceptor, the toxin-induced Ca2+ uptake and toxin-stimulated neurotransmitter release. A separate part of alpha-latrotoxin molecule is responsible for the formation of cationic channels in the artificial lipid bilayer.
Pashkov
V
V
Branch of Shemyakin Institute of Bioorganic Chemistry, Academy of Sciences of Russia, Moscow.
Grico
N
N
Tsurupa
G
G
Storchak
L
L
Shatursky
O
O
Himmerlreich
N
N
Grishin
E
E
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008051:Lipid Bilayers; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010539:Permeability; D051381:Rats; D013111:Spider Venoms / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000633:toxicity; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000911:Antibodies, Monoclonal; D007457:Iodine Radioisotopes; D007473:Ion Channels; D008051:Lipid Bilayers; D018377:Neurotransmitter Agents; D013111:Spider Venoms; D005680:gamma-Aminobutyric Acid; C020763:alpha-latrotoxin; D002118:Calcium