Journal article
Binding of monovalent cations to phosphatidylserine and modulation of Ca 2+- and Mg 2+-induced vesicle fusion
Biochimica et biophysica acta. Biomembranes, v 735(1)
1983
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
The effect of several monovalent cations on the Ca
2+-induced aggregation and fusion of sonicated phosphatidylserine (PS) vesicles is studied by monitoring the mixing of internal compartments of the fusing vesicles using the Tb/dipicolinic acid assay. The dissociation of the fluorescent Tb-dipicolinate complex which accompanies Ca
2+-induced vesicle fusion is determined directly and is due to leakage of contents and entry of medium into vesicles. PS vesicles do not fuse when the medium contains only monovalent cations (at pH 7.4), regardless of the cation concentration or whether there is aggregation of the vesicles. A mass-action kinetic analysis of the data provides estimates for the rate of aggregation,
C
11
, and for the rate of fusion per se,
f
11
. Values of
f
11
increase dramatically with reduction in monovalent cation concentration and are primarily determined by binding ratios of Ca
2+ or Mg
2+ per PS. With 300 mM of monovalent cations, the fusion per se is essentially rate-limiting to the overall fusion process and values of
f
11
are significantly larger with the monovalent cations which bind the least, i.e., according to the sequence tetramethylammonium
>
K
+ > Na
+ > Li
+
. With monovalent cations in concentrations of 100 mM or less, the aggregation is rate-limiting to the fusion and the overall initial fusion rates are determined by an interplay between aggregation and fusion rates. Under conditions of fast aggregation, the Ca
2+-induced fusion of small PS vesicles can occur within milliseconds or less.
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Details
- Title
- Binding of monovalent cations to phosphatidylserine and modulation of Ca 2+- and Mg 2+-induced vesicle fusion
- Creators
- Shlomo Nir - University of California, San FranciscoNejat Düzgüneş - Cancer Research InstituteJoe Bentz - University of California, San Francisco
- Publication Details
- Biochimica et biophysica acta. Biomembranes, v 735(1)
- Publisher
- Elsevier
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biology
- Web of Science ID
- WOS:A1983RQ77300017
- Scopus ID
- 2-s2.0-0021113451
- Other Identifier
- 991021463319304721
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InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Web of Science research areas
- Biochemistry & Molecular Biology
- Biophysics