Molecular Anatomy of Synaptic Vesicles

A brownian dynamics interpretation of membrane protein clustering

Most plasmalemmal proteins organize in submicrometer-sized clusters whose architecture and dynamics are still enigmatic. With Syntaxin 1 as an example, we applied a combination of far-field optical nanoscopy, biochemistry, fluorescencerecovery after photobleaching (FRAP) analysis, and simulations to show that clustering can be explained by self-organization based on simple physical principles.

On average, the syntaxin clusters exhibit a diameter of 50 to 60 nanometers and contain 75 densely crowded syntaxins that dynamically exchange with freely diffusing molecules. Self-association depends on weak homophilic protein-protein interactions. Our simulations suggest that clustering immobilizes and conformationally constrains the molecules. Moreover, a balance between self-association and crowding-induced steric repulsions is sufficient to explain both the size and dynamics of syntaxin clusters and likely of many oligomerizing membrane proteins that form supramolecular structures.


Sieber, J. J.; Willig, K. I.; Kutzner, C.; Gerding-Reimers, C.; Harke, B.; Donnert, G.; Rammner, B.; Eggeling, C.; Hell, S. W.; Grubmüller, H. et al.; Lang, T.: Anatomy and dynamics of a supramolecular membrane protein cluster. Science 317 (5841), pp. 1072 - 1076 (2007)
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