Divalent cation, ATP-dependent [3H]leu-enkephalin uptake by synaptic vesicle fraction isolated from bovine caudate nucleus.
The mechanism of [3H]Leu-enkephalin uptake into synaptic vesicle fraction from bovine caudate nucleus was investigated. The simultaneous addition of 2 mM MgCl2, 2 mM CaCl2, and 2 mM ATP stimulated the uptake 22 times over the control, whereas the separate addition of these agents augmented the uptake 2.4 times at most. The addition of 2 mM MGCl2 plus 2 mM ATP and of 2 mM CaCl2 plus 2 mM ATP increased the uptake 6.6 times and 4.5 times, respectively. The cation, ATP-dependent uptake reached its half-maximal level within 10 min after the initiation of incubation at 25 degrees C, and little Leu-enkephalin was taken up at 0 degree C. The apparent Km for the uptake of [3H]Leu-enkephalin was 1.8 x 10(-7) M. Guanosine triphosphate stimulated the uptake as well as ATP, whereas CTP and ITP were only one-fourth effective of ATP. The cation, ATP-dependent uptake was inhibited by 25% and 20% in the presence of 0.1 mM colchicine and 1 microM reserpine, respectively.
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism*; D004573:Electrolytes / Q000494:pharmacology*; D004723:Endorphins / Q000378:metabolism*; D004743:Enkephalin, Leucine; D004745:Enkephalins / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism*; D013696:Temperature
D004573:Electrolytes; D004723:Endorphins; D004745:Enkephalins; D004743:Enkephalin, Leucine; D000255:Adenosine Triphosphate; D008274:Magnesium; D002118:Calcium