ATP‐Stimulated Ca2+ Transport into Cholinergic Torpedo Synaptic Vesicles

• DOI: 10.1111/j.1471-4159.1980.tb12496.x
• Publication Date: 2006-12-13T12:56:08Z
• Authors: D. M. Michaelson; I. Ophir; I. Angel
• Keywords: Nigericin; Valinomycin; Protonophore; Ruthenium red; Vesicular Transport Proteins

Activation of the Ca2+/Mg2+ ATPase associated with highly purified Torpedo synaptic vesicles results in 45Ca2+ uptake. The accumulated is released by hypoosmotic buffer and Ca2+ ionophore A23187. Density-gradient centrifugation permeation chromatography reveal that vesicular acetylcholine membrane-bound co-migrate, thus implying transported into cholinergic vesicles. ATP-dependent uptake follows saturation kinetics, KmCa2+ = 50 microM, Vmax 3 +/- 0.3 nmol Ca2+/mg protein/min. Treatment mersalyl, dicyclohexylcarbodiimide, quercetin leads to inactivation comparable inhibition transport. Ruthenium red ouabain have no effect on either these activities. Nigericin presence external K+ a potent inhibitor translocation, whereas gramicidin activates proton translocator carbonylcyanide p-trifluoromethoxy-phenylhydrazone (FCCP) FCCP + valinomycin partially inhibit By contrast, above ionophores do not affect activity. Tentative mechanisms for transport physiological significance this process are discussed.