The Journal of Membrane Biology

, Volume 40, Issue 4, pp 343–364

Fusion of secretory vesicles isolated from rat liver

  • Manfred Gratzl
  • Gerhard Dahl

DOI: 10.1007/BF01874163

Cite this article as:
Gratzl, M. & Dahl, G. J. Membrain Biol. (1978) 40: 343. doi:10.1007/BF01874163


Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10−6m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells.

Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system.

The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences.

Copyright information

© Springer-Verlag New York Inc 1978

Authors and Affiliations

  • Manfred Gratzl
    • 1
  • Gerhard Dahl
    • 1
  1. 1.Departments of Physiological Chemistry and Physiology IUniversity of SaarlandHomburg/SaarGermany