Table S2.
Exact protein masses as determined by denaturing LC-MS
| Subunit | Theoretical mass (Da) | RT (min) | Experimental mass (Da) | Δ Mass (Da) | |
| With transit peptide | Without transit peptide | ||||
| I | 57,032 | 57,032 | / | / | / |
| II | 26,021 | 26,020 | 52.3-57.9 | 26,199 | 179 |
| III | 29,933 | 29,940 | / | / | / |
| IV | 19,572 | 17,150 | 35.8-37.8 | 17,297 | 147 |
| Va | 16,735 | 12,440 | 33.0-36.1 | 12,518 | 78 |
| Vb | 13,834 | 10,670 | 28.0-35.8 | 10,775 | 105 |
| VIa | 10,800 | 9,530 | 32.6-33.1 | 9,376 | -154 |
| VIb | 10,156 | 10,030 | 27.0-29.6 | 10,094 | 64 |
| VIc | 8,610 | 8,480 | 29.6-31.5 | 8,615 | 135 |
| VIIa | 9,063 | 6,670 | 31.3-31.9 | 6,713 | 43 |
| VIIb | 9,065 | 6,360 | / | / | / |
| VIIc | 7,331 | 5,440 | 33.0-37.8 | 5,469 | 29 |
| VIII | 7,639 | 4,960 | 33.0-35.8 | 4,978 | 18 |
| Σ | 225,791 | 204,722 | 205,366 | 644 | |
The theoretical masses obtained from the UniProt database, the retention time during LC-MS, the experimental masses, and the mass differences are given for each protein subunit. For proteins that contain a transit peptide, the masses with and without transit peptide are given. Subunits VIb and VIc include an initiator methionine, which is removed. Note that some proteins eluted over several minutes and multiple mass spectra were obtained. For these proteins the average masses were calculated. Subunits I, III, and VIIc were not identified by denaturing LC-MS.