TY - JOUR
T1 - pH-Dependent fusion of synaptosomal membrane studied by fluorescence quenching method
AU - Kumamaru, Emi
AU - Sato, Masayuki
AU - Yoshida, Hiroko
AU - Ide, Toru
AU - Kasai, Michiki
PY - 1999/2
Y1 - 1999/2
N2 - We have found that both the synaptic vesicles (SV) and synaptic plasma membrane vesicles (SPM) have an activity to fuse with phosphatidylcoline/phosphatidylserine liposomes in a pH-dependent manner. The activity increases with decreases in extravesicular pH. At a pH lower than 4.0, the activity is almost steady at its maximum value, and there was a rapid drop around pH 5.5. The pH-dependent fusion was inhibited by proteolysis with trypsin; hence, at least in part, some membrane proteins play an important role in these pH-dependent fusion processes. To find specific markers, we screened various protein modifiers and found that anion channel blockers, stilbene derivatives (DIDS and SITS) and glibenclamide, affected the fusion process. DIDS and SITS decreased the fusion activity with an IC50 of 180 and 300 μM, respectively, whereas glibenclamide, on the contrary, increased it. From the results of an autoradiogram using 3H- tagged DIDS, a 30 kDa DIDS-binding protein was identified in the synaptic plasma membrane, which is possible to be responsible for the pH-dependent fusion.
AB - We have found that both the synaptic vesicles (SV) and synaptic plasma membrane vesicles (SPM) have an activity to fuse with phosphatidylcoline/phosphatidylserine liposomes in a pH-dependent manner. The activity increases with decreases in extravesicular pH. At a pH lower than 4.0, the activity is almost steady at its maximum value, and there was a rapid drop around pH 5.5. The pH-dependent fusion was inhibited by proteolysis with trypsin; hence, at least in part, some membrane proteins play an important role in these pH-dependent fusion processes. To find specific markers, we screened various protein modifiers and found that anion channel blockers, stilbene derivatives (DIDS and SITS) and glibenclamide, affected the fusion process. DIDS and SITS decreased the fusion activity with an IC50 of 180 and 300 μM, respectively, whereas glibenclamide, on the contrary, increased it. From the results of an autoradiogram using 3H- tagged DIDS, a 30 kDa DIDS-binding protein was identified in the synaptic plasma membrane, which is possible to be responsible for the pH-dependent fusion.
KW - Membrane fusion
KW - Synaptic vesicle
KW - Synaptosome
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U2 - 10.2170/jjphysiol.49.19
DO - 10.2170/jjphysiol.49.19
M3 - Article
C2 - 10219105
AN - SCOPUS:0032954971
VL - 49
SP - 19
EP - 25
JO - Journal of Physiological Sciences
JF - Journal of Physiological Sciences
SN - 1880-6546
IS - 1
ER -