Adenosine triphosphate-dependent calcium uptake of synaptic vesicle fraction is largely due to contaminating microsomes.
Ca2+ uptake by synaptic vesicle fractions isolated from bovine caudatolenticular nuclei and from rat brain was studied. The purified vesicle fractions from both materials took up very little Ca2+ even in the presence of ATP and Mg2+, but the crude fractions took up Ca2+ actively, showing the maximum uptake around pH 7.0. Since the crude fractions were contaminated by microsomes, which are known to accumulate Ca2+ actively (Yoshida, H., Kadota, K., & Fujisawa, H. (1966) Nature 212, 291--292; Otsuka, M., Ohtsuki, I., & Ebashi, S. (1965) J. Biochem. 58, 188-190), the active uptake of Ca2+ appeared to be largely, if not wholly, due to microsomal contamination.
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002421:Caudate Nucleus / Q000378:metabolism / Q000648:ultrastructure; D003342:Corpus Striatum / Q000378:metabolism / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D008274:Magnesium; D008861:Microsomes / Q000378:metabolism*; D051381:Rats; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure
D000255:Adenosine Triphosphate; D008274:Magnesium; D002118:Calcium