Figure 4. Mass spectrometry analysis of proteins present in low-density vesicular fractions obtained from OptiPrep® ultracentrifugation. Fractions 2 and 3 obtained from subcellular fractionation were combined, subjected to ultracentrifugation for isolation of membrane-associated proteins and separated by SDS-PAGE. In-gel-digestion products were analyzed with LC-MS. (A) Silver staining of membrane-associated proteins resolved by SDS-PAGE. Lane 1, Molecular weight protein standard; lane 2, membrane-associated proteins from combined fractions 2 and 3. Numbers 1 through 14 correspond to gel fragments subjected to in-gel digestion. (B) Proteins identified by LC-MS analysis. A total of 212 proteins were identified and categorized into 10 groups. Numbers in brackets correspond to number of identified proteins belonging to each category. Proteins corresponding to each category, identified with the highest score and shown in the Table II are listed.
