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Effect of N,N ‐Dicyclohexylcarbodiimide on Acetylcholine Release from Torpedo Synaptosomes and Proteoliposomes Reconstituted with the Proteolipid Mediatophore
Author(s) -
Sbia Mohammed,
Diebler MarieFrancoise,
Morel Nicolas,
Israël Maurice
Publication year - 1992
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1992.tb08437.x
Subject(s) - torpedo , acetylcholine , protein subunit , chemistry , biochemistry , atpase , phospholipid , biophysics , membrane , acetylcholine receptor , biology , enzyme , pharmacology , receptor , gene
The mediatophore is a presynaptic membrane protein that has been shown to translocate acetylcholine (ACh) under calcium stimulation when reconstituted into artificial membranes. The mediatophore subunit, a 15‐kDa proteolipid, presents a very high sequence homology with the N,N′ ‐dicyclohexylcarbodiimide (DCCD)‐binding proteolipid subunit of the vacuolar‐type H + ‐ATPase. This prompted us to study the effect of DCCD, a potent blocker of proton translocation, on calcium‐dependent ACh release. The present work shows that DCCD has no effect on ACh translocation either from Torpedo synaptosomes or from proteoliposomes reconstituted with purified mediatophore. However, using [ 14 C]DCCD, we were able to demonstrate that the drug does bind to the 15‐kDa proteolipid subunit of the mediatophore. These results suggest that although the 15‐kDa proteolipid subunits of the mediatophore and the vacuolar H + ‐ATPase may be identical, different domains of these proteins are involved in proton translocation and calcium‐dependent ACh release and that the two proteins have a different membrane organization.