Article
- The EMBO Journal (2001) 20, 2202 - 2213
- doi:10.1093/emboj/20.9.2202
SNAREs are concentrated in cholesterol-dependent clusters that define docking and fusion sites for exocytosis
Thorsten Lang1, Dieter Bruns1, Dirk Wenzel1, Dietmar Riedel1, Phillip Holroyd1, Christoph Thiele2 and Reinhard Jahn1
- Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 110, D-01307 Dresden, Germany
Correspondence to:
Reinhard Jahn, E-mail: rjahn@gwdg.de
Received 25 January 2001; Accepted 2 March 2001; Revised 2 March 2001
Abstract
During exocytosis, SNARE proteins of secretory vesicles interact with the corresponding SNARE proteins in the plasmalemma to initiate the fusion reaction. However, it is unknown whether SNAREs are uniformly distributed in the membrane or whether specialized fusion sites exist. Here we report that in the plasmalemma, syntaxins are concentrated in 200 nm large, cholesterol-dependent clusters at which secretory vesicles preferentially dock and fuse. The syntaxin clusters are distinct from cholesterol-dependent membrane rafts since they are Triton X-100-soluble and do not co-patch with raft markers. Synaptosomal-associated protein (SNAP)-25 is also clustered in spots, which partially overlap with syntaxin. Cholesterol depletion causes dispersion of these clusters, which is associated with a strong reduction in the rate of secretion, whereas the characteristics of individual exocytic events are unchanged. This suggests that high local concentrations of SNAREs are required for efficient fusion.
Keywords:
- cholesterol,
- exocytosis,
- PC12 cells,
- SNAREs
