The carboxy-terminal domain of complexin I stimulates liposome fusion

Jörg Malsam, Florian Seiler, Yvette Schollmeier, Patricia Rusu, Jean Michel Krause, Thomas H. Söllner

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52 Citations (Scopus)


Regulated exocytosis requires tight coupling of the membrane fusion machinery to a triggering signal and a fast response time. Complexins are part of this regulation and, together with synaptotagmins, control calcium-dependent exocytosis. Stimulatory and inhibitory functions have been reported for complexins. To test if complexins directly affect membrane fusion, we analyzed the 4 known mammalian complexin isoforms in a reconstituted fusion assay. In contrast to complexin III (CpxIII) and CpxIV, CpxI and CpxII stimulated soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-pin assembly and membrane fusion. This stimulatory effect required a preincubation at low temperature and was specific for neuronal t-SNAREs. Stimulation of membrane fusion was lost when the carboxy-terminal domain of CpxI was deleted or serine 115, a putative phosphorylation site, was mutated. Transfer of the carboxy-terminal domain of CpxI to CpxIII resulted in a stimulatory CpxIII-I chimera. Thus, the carboxy-terminal domains of CpxI and CpxII promote the fusion of highcurvature liposomes.

Original languageEnglish
Pages (from-to)2001-2006
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number6
Publication statusPublished - 10 Feb 2009
Externally publishedYes


  • Exocytosis

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