Targeted mass spectrometry based quantification and characterization of SNARE complex proteins from human brain tissue

摘要

The membrane-bound and membraneraft-associated SNAP-25 was found to be primarily modified by methionine excision and acetylation and tightly bound to the other SNARE complex. Soluble SNAP-25, on the other hand, consisted predominantly of truncated forms. These soluble forms of SNAP-25 did not co-immunoprecipitate with the other SNARE complex proteins. With the top-down approach eight different truncated forms of soluble SNAP-25 ranging in size from 2.3 to 5.4 kDa and modified by methionine excision and acetylation were identified. A comparison of SNAP-25, syntaxin-1A, syntaxin-1B, and VAMP-2 concentrations between AD and controls were performed with SRM-MS. All proteins showed a significant decrease in the.