The multisubunit structure of synaptophysin. Relationship between disulfide bonding and homo-oligomerization.

摘要: Synaptophysin, a major membrane protein of synaptic vesicles, contains four transmembrane regions and two intravesicular loops. Synaptophysin monomers associate into homopolymers that have the potential to form channels in vesicle membrane. Here we show native synaptophysin, are linked by noncovalent forces. The molecule unstable intramolecular disulfide bonds undergo exchange during solubilization, thereby covalently cross-linking neighboring synaptophysin molecules. locations were determined, revealing each loops is circularized single bond. Cross-linking can be triggered vesicles intact cells cycle reduction oxidation, suggesting homomultimer situ. In addition, chemical demonstrates low molecular weight specifically associated with complexes lost upon bonds. These data suggest forms homomultimeric complex whose structure interaction other proteins dependent on integrity its phospholipid environment.