Expression of receptor for α-latrotoxin in Xenopus oocytes after injection of mRNA from rat brain

α-Latrotoxin, the major toxin of black widow spider venom, was suggested to bind to the specific receptor on the membrane of presynaptic cells and to activate a nonselective cation channel. The aim of this investigation was to express the receptor to α-latrotoxin in the membrane of Xenopus laevis oocytes. Responses to α-latrotoxin were studied using a double microelectrode voltage-clamp techniqe on X. laevis oocytes previously injected with poly(A +)-RNA from rat brain. α-Latrotoxin (10 nM) was shown to induce a slow activating reversible inward membrane current at a clamp potential of −60 mV. A second application of α-latrotoxin immediately after washing out induced a smaller response. Reversal potential of this current was near to 0 mV; it hardly changed in low Cl − external solution. Response to α-latrotoxin did not depend significantly on the variation of Ca 2+ concentration in external solution. Ethyleneglycolbis(aminoethylether)tetra-acetate (EGTA) injection into oocytes did not decrease α-latrotoxin-induced current, but seemed to slow the kinetics of the response. Inorganic Ca-channel blocker Co 2+ had no effect on a-latrotoxin response. These results indicate that α-latrotoxin-induced inward current flows mainly through cation nonspecific channel. A lectin concanavalin A irreversibly inhibited α-latrotoxin-evoked inward current. Many of these observations are similar to those reported for nerve cells after α-latrotoxin application. The data obtained suggest that functional receptor to α-latrotoxin can be successively expressed in the membrane of Xenopus oocytes providing future search of DNA encoding receptor subunits and study of receptor structure-function relationship.